Doesn't really matter how many channels you need vs what the best values/features will be in an avr, you may get some features/channels you don't need but depends somewhat on just what you do need, just the nature of economies of scale. Besides the limited audio setup, do you need 4k video feature set? What do you need it to do other than power your speakers? Used avrs could be a possibility depending on the feature set needed.
Most new ones will be for more than only 5.1 setups, 7/9/11 channel feature sets are more the norm now. Maybe a limited feature set pre-pro like an Outlaw 976 instead and get a 5ch amp instead. What's the budget? If its a small space why do you need a power amp ?
Generally an avr will have a full set of pre-outs rather than just L/C/R (a few may have pre-outs just for L/R and subs), and this is typically found in the mid to higher end range of avrs in any case.