Originally Posted by bmthom.gis

I would say it depends on how long your commute is going to be, and what kind of trails you want to ride. You should post over in the commuter sub.

Definitely go with a used steel bike. For your budget, it will be much better than anything you can find new. Mountain bikes from the 80s and 90s with rigid forks make good commuters if you aren't going super long. They will work for long distances also, but my preference is a bike with drop bars (you could do a drop bar conversion). There are plenty of pretty good road bikes out there that sell in the 125-150 price range. Shoot, you can get 2 bikes for only a little over your budget, and sell one of them for easily 150-175 (the Volpe is a terrific commuter and all around bike). If those were my size I would have told family in the area to scoop them up for me.

https://baltimore.craigslist.org/bik/5012242852.html

Things you would want most if you go road bike (older ones tend to be able to take wider tires, FYI) are 700C wheels...27" wheels really limit tire choices, as do 650s and alloy rims.