What brands are in the dealers in your area?
Realistically if you go to a bike shop or several, at the $500 price point,
the bikes will be similar, only the brand name differs.
the component picks will be on average similar,
as the makers of the component parts have their several price points..
and so the bits chosen , pre-dominantly shimano's, will match the price level.
shop the dealer for service after the sale then ride the bike..
a good bike shop would fit you on a well sized bike,
and fit a few accessories to make the commute go well..