What's the purpose of switching frequent flyer programs? Are you simply interested in reward redemptions or does having status with them (and by connection the Star Alliance) matter? I will address each of these in turn.
If you're interested in purely award redemptions on flights (and not on toasters as QF seems to think we're interested in), an argument could be made to sign up for Singapore. After all, Singapore operates more international routes out of Australia than Qantas does. At the same time, as they are part of Star Alliance, they have access to the most comprehensive route network in the world (Star Alliances has 26 member airlines globally covering all of North America and Europe, along with decent coverage of Africa, LATAM and Asia). So in terms of finding award itineraries that work for you, they could potentially be a valuable reward partner to credit to. There may also be some sweet spots in redemptions that QF doesn't offer, although that will depend on if you actually fly in said sweet spots and whether there is availability to line up. I also hear that Singapore doesn't have the same obscene taxes and surcharges that QF applies (i.e. the eye watering amount to have the privilege of flying Emirates).
What is key in terms of reward redemptions, is to do your research beforehand on the routes you plan on flying and ideally transferring miles to these programs as you see availability to take the flights you want. Personally, and perhaps controversially, I'm actually signed up to a number of frequent flyer programs for this exact purpose: American, Delta, United, Air Canada, Lufthansa, British Airways, Qantas, Virgin Australia, ANA MilagePlan, etc. Then depending on the trip I'll move miles in from my AmEx card (or other transferrable milage program) to the frequent flyer account in question. Sometimes the airlines will also run promotions where you can purchase miles on the cheap. To give you a fairly recent example, Air Canada's Aeroplan was running a promotion until very recently where you could buy points for effectively 1.75 cents per point. I ended up buying 130,000 miles for ~$2,200 CAD to pull my Aeroplan account up to 160,000. With that many points I was able to find an award business class ticket from Sydney to Toronto for 160,000 miles return + $300 in taxes and fees. I don't know about you folks, but spending $2,500 to travel return in J seems like a good deal to me (for comparison on Qantas you'd easily spend $2,200 AUD to fly Qantas in Economy to Toronto from Sydney).
Now if you're going for frequent flyer status, the first thing you need to ask yourself is why? Why does frequent flyer status matter to you? A lot like the sound of Gold, 1K or Global Services but rarely end up using the benefits of the status they worked so hard to earn, particularly when you consider that on most frequent flyer programs you need to spend considerable change (i.e. $1000s) annually just to maintain the status you are on. My recommendation is to reflect on your pre-COVID travel and see where you spent your money, particularly on ancillaries like seat selection and baggage. In my case, back in 2019 it made plenty of sense to fly exclusively Star Alliance to keep my United status since $2,300 CAD of flights worked out to the 50,000 flown miles I needed to keep my Gold status. During that time, I would somewhat regularly be flying between Europe and North America with luggage (sometimes as many as 3 checked bags). Knowing that on my £249 basic economy United fare, I can check 2 or 3 bags in free no problem was great value. Similarly, flying those long routes like Heathrow to LA where you are onboard for 10+ hours, having access to an overwing exit seat with its 50+ inch leg room and paying nothing (as opposed to the hundreds you would ordinarily spend for such a luxury) was also great value for me. There is something to be said for having a window seat and being able to get out of that seat without waking anyone up or having to step over anyone. Then there were some benefits available that I would sparingly use but would find very useful when I needed to. Case in point, I needed to stay an extra day at a conference I was attending in San Diego. Ordinarily this would have resulted in change fees and fare differences. However, United provides free same-day changes, so it was quick work for me to change my flight to the following day over the phone and BTW I wasn't waiting hours to speak with a representative, either! The occasional upgrade to J on domestic US flights with United was nice too. I can remember a red eye I had with United flying from Agaudilla, Puerto Rico to Newark, departing at 1:30 AM, and being in that front row window seat where I can doze off after having some booze really took the bite out of that trip. Lounges were also a nice benefit, particularly if I was outside the US, far away from those dumps called United Clubs. Then there were the matched Gold status with Marriott which I have used whenever I stay with them to get that 2 PM late checkout. Overall, I would value the benefits attaining status on United far outweighed the cost of staying Alliance loyal. Again, I'd encourage everyone thinking about status to really look at the cost and benefits before jumping in to the program. The last thing you want to do is spend thousands or even tens of thousands chasing status in a year without making use of the benefits earned.
In terms of which frequent flyer program offers the best status or benefits, that really depends on what benefits you are looking for and how much money you are willing to spend. Different airlines have different requirements for earning status. For instance, Delta Airlines in the 'States only cares about total miles flown in a given program year with Delta, SkyTeam alliance members like KLM/Air France, and other partners like WestJet in Canada if you are an overseas member. It would therefore, not be too difficult to rack up the 50,000 miles flown to earn Delta Gold status (their mid-tier benefit), particularly given the fact that any economy (aside from basic economy) Delta seat earns you 100% milage flown for status (and potentially 200% or more depending on fare class and airline). Contrast this with other programs where you need to fly a lot more to earn similar mid-tier status (i.e. Lufthansa Senator's 100,000 mile requirement) or is based purely on how much money you spend with the airline (i.e. Air Canada's SQD's). Benefits also vary from program to program as well. For instance, having any status on Qantas does not give you complimentary upgrades to business on domestic flights. However, with other programs like United that is the case. Then again, you need to be flying a decent amount in the US to really use that benefit. Things like complimentary preferred seating may also only apply to the airline you hold status for. Hence, as a general rule of thumb try and earn status on those airlines that you intend on flying with frequently to maximize benefits, if it makes to credit the flights with them. Other benefits, like security fast track, extra baggage allowance, lounge access and priority customer service apply alliance wide and can be quite beneficial even when you're not flying with the airline you hold status with. For instance, in 2019 I was flying domestically with Air Canada (a member of Star Alliance, which United is also a member of), I ended up being stranded overnight in Montreal due to IRROPs. Ordinarily if I didn't have status I would have had to spend money out of pocket for a hotel and meals. However, due to my Star Alliance Gold status with United, I was entitled to a free hotel and meals and received both after visiting the ticketing desk in Montreal.
Looking forward, and having been on the status treadmill for sometime, I plan on actually earning mid-tier status across all alliances (SkyTeam, OneWorld and Star Alliance). For me mid-tier status is just the right balance of benefits: you have all the benefits you'll consistently use (seat assignment, extra baggage, lounge access), without spending a whole lot of money out of pocket. Part of the reason I plan on landing status across all three alliances is flying ex-Australia internationally isn't as simple as flying ex-Europe internationally. There are fewer airlines that fly here and often the cheapest airline won't be in the alliance I have status for. For instance, Delta or Air Canada regularly beats QF and AA on fares to North America. In order to pull this off I need to be very strategic in how I make my bookings now. Starting this year I have OneWorld (QF) and Star Alliance (UA) mid-tier status and will (hopefully) status match my UA to Delta on July 1 to earn status through January 2024. QF status has already been sorted as they required just taking one flight this year with them (which I've already done). UA status is secured through the end of the year, and I'll let it lapse for 2023, using a status match with United, when I plan on flying Star Alliance again. SkyTeam will be acquired through a status match to Delta and me flying a $2000 AUD flight on KLM J between Toronto and Glasgow in late July. So all in all, come July I will have mid-tier status with all three alliances for approximately $2200 AUD spend ($200 AUD spend on QF and $2000 AUD spend on KLM for DL status).
Hope that provides some value.
-RooFlyer88