I need help with this decision.?

Okay well I went and signed up for the Army DEP today. I will more than likely get a 20,000 dollar signing bonus. I joined the reserves so I could be sure I could get my degree. I locked my job in 21B as a combat engineer. My question now is I feel confused I mean they give you so much paper work at once and just say everythings okay but I just don't know. I was looking into the Air Force but joining with the Air Force gives you no signing bonus and slow rank. I love the military in general and would be happy with what I do regardless, I just don't want to wish I would've went with the other option if you know what I mean. I know this is a decision on my part and you guys can't really help me with it but personal opinions is what I'm looking for. Thanks for the help.