I am brand new to cycling. Just getting my first bike. I want something to supplement my running and commute. I need to find something under $500. I've got a couple bikes (Jamis Ventura Sport, Airborne Thunderbolt) that I can get for around $300. Which would you rather ride, are they suitable for what I'm looking to do, and which is the better value? Airborne has Shimano 105, Jamis has Tiagra. Thanks for the guidance.