Hello,
I am student and have to ride 7-8miles a day most of the part on road and around 0.5 mile offroad.
I tried mountain bike it was too exausting for me and road bike was little uncomfortable especially off road.
I decided to go with comfort/hybrid/dual-sport bike.
I need durable bike which will need less effort to ride, and low maintenance.

Polaris Sportsman Men's Comfort Bike
Polaris Sportsman 26" Mens Comfort Bike - Walmart.com

Hyper SpinFusion Adult Fitness Bike
700C Hyper Spinfusion Adult Hybrid Bike - Walmart.com

NEXT Avalon Men's Comfort Bike with Full Suspension (also getting same one used for $50)
Avalon Men's 26" Cruiser Bike - Walmart.com

700c Schwinn Men's DSB Dual Sport Bike
Purchase the Schwinn 700c Road Bike, DSB Dual Sport for less at Walmart.com. Save money. Live better.

Diamondback Adult Wildwood Citi Classic Comfort Bike (getting used one too, 2008 model for $140 on community mentioned below)
Diamondback Wildwood Citi | DICK'S Sporting Goods

there is some bike on sell on local community. They do have some used bike on sale and some for free.
R Community Bikes, Bikes for Sale. Can?t Keep Site Up to Date!

I am not sure from where should I buy or which one?
used one or new one?