I fly Rex almost every week,and I also fly Qlink regularly,Rex uses Saabs that are getting a bit long in the tooth and Qlink uses Dash 8's and have ordered new Q400's which are supposed to be quieter and more comfortable,as regards catering both airlines are pretty much the same,on morning flights from ABX to MEL which I take regularly they serve coffee and biscuits which is similar to what Qlink gives you on mid morning and afternoon flights.
If Qlink operated the ABX to MEL route I would probably fly with them instead of Rex but only for the FF points,the Rex FF scheme is currently suspended and has been since late last year,this is due to a "revamp" it was supposed to be relaunched in January but nothing has happened.
Cheers
N'oz