General comments about components in that price range: They will all be pretty similar, provided that you are looking at 8-speed or 9 speed cassettes. Typical base models are 7-speed cassettes (typically listed as 21 speed bikes). which makes for big jumps when shifting.

Wheels are all going to be basic OEM wheels, that you could buy for $100 or less, if they are even sold to the public. Shifters and derailleurs are going to be Shimano or SRAM, which are very comparable and totally a matter of preference. My Sirrus started with Alivio (shimano) components and my son's has SRAM X4 stuff: no real difference.

Get what fits and what you like the looks of. In a $600 or less LBS bike, some may be slightly better equipped than others, but unlikely would the difference be appreciable.