To be honest, I'm actually using my Amex cards less than before.
I now book Qantas flights using my HSBC QF Visa because the earn rate is better (2 QFF/$1, versus 1.75/$1 on QF Discovery or 1.125/$1 on Amex Plat).
I now use CBA Ultimate overseas because the earn rate is higher (3 CBA/$1, equal to 1 SQ mile per AUD $1, versus 2.25 MR/$1 on Plat, equal to 0.75 SQ miles per AUD $1) - and for that, CBA also has no foreign fee and is accepted anywhere Mastercard is, versus Amex with worse acceptance in many countries and a 3% fee when it is accepted.
I often use my Visa/MC in restaurants and cafes because I find many places now have auto surcharging on the terminal and it's all set to mirror the acceptance cost, and Amex fees tend to be double the surcharge of Visa/MC but the earn rate on Amex is barely a fraction more and not worth paying double for.
I could list plenty of other examples by category, but you get the idea. I obviously still use my Amex cards, but nowhere near as much as before. They've just cut back on so many of the reasons to use Amex and so many of the things that made Amex 'Amex'. Now it's kinda just a glorified credit card with worse acceptance and not significantly more points to make it worth it. Rant over.