What is a suitable Gear Range for Biking on Flat Rail Trails
Comfort oriented hybrid bikes are good for recreational riding on smooth prepared trails without steep hills.

7 speed bikes are simpler, but without a choice of front sprockets you will want to be sure that the gear range they offer suits you. Getting a good test ride on any bike you are considering is recommended.

One thing I would avoid is front suspension. At the price range of the bikes you mention they don't provide much damping but do add weight.