I don't think there are really any "bad" cars out there, at least as far as recommending brands. However this is one case where "you get what you pay for".......a $10 Atlas Trainman car will not be as nice as a $20 Atlas car, so you can't just say "Atlas is great" because there are different series of cars at different quality levels....a lot depends on what you expect from your cars....there are still people out there who prefer Rapido couplers because they match what they already have, but most cars with Rapidos are at the lower end of the quality scale. Another factor that enters in is simply what you're looking for.......for example Athearn makes some nice old-time passenger cars, but no newer styles.....Bachman is the only company who makes excursion type passenger cars....sometimes you'll have no choice because only one company may make the car you want, or the company you prefer may not make the car you want. If you're looking for kits, I think Intermountain is the only company still doing them, although there are a few small companies who make shells, car sides, ect so you can build your own cars. Any car can be upgraded.......but why buy a $10 car and spend $10 on upgrades if there's a $20 car that has all the features you want....unless doing the detailing yourself is something you really enjoy (I know people like that).