bigboi1881 said:I plan to use the bike for basic riding around town, parks, and also for exercise. Im pretty big 6'1" 210lbs so I think I need a mountain bike, also something on the lighter side.
6'1" and 210 lbs is not too big for most entry level road bikes or hybrids. I am down to 229 (from 262, on my way to 180 😉 ), and I ride a Specalized Crossroads. The Trek 7200 is a similar, entry level hybrid. As long as the wheels have 32 or 36 spokes and are not ultra light (which you will not find in your price range, anyway) there should be no problems with your weight.
The choice of a mountain bike, hybrid (and which hybrid) or road bike should depend on where you will be riding. Road bikes are strictly for paved surfaces. Hybrids with 700 cm wheels and larger chainrings, like the Specalized Crossroads or Trek 7x00 series are good for well maintained, but unpaved, bike paths. They are slower and heavier than road bikes, but not nearly as slow or as heavy as a true mountain bike or the more mountain bike-like hybrids, like the Specalized Expedition or Trek Navigator series (26 in wheels and smaller chainrings than the Crossroads or 7x00 series). Mountain bikes are for true off-road use.
I agree with others that of the brands you listed, I would go with Schwinn or Mongoose, but keep looking and see if you cannot find a store within an hour's drive that carries such brands as Trek, Specialized, Giant, or Cannondale. These all have entry level bicycles in the $300 to $375 range that would fit your needs. While there is nothing wrong with Schwinn or Mongoose, it is worth driving an hour to find a shop that will help you decide which style is best for you, find the proper fit for you, set the bike up correctly for you, and let you try the bike out before you buy. The one thing worse than driving for an hour and spending $375 on a bicycle that you will enjoy riding is shopping locally and saving $75 on a bike that sits in the garage because it is not the right bike for you.