Onkyo is budget (and normally only do AVRs rather than stereo amps). NAD and Marantz usually are the go-to brands in the higher price ranges. For budget amps I'd recommend Cambridge Audio and for budget speakers usually Wharfedale, although obviously there are other budget brands too those are what I've personally preferred.
I have very positive experience of Harman/Kardon too, I'm not sure what price their amps start but worth checking out second hand I'd reckon along with retro speakers; I managed to get myself 4 Sony speakers from the late 70s for peanuts and they sound amazing, you just have to keep your eyes open for bargains.