Used Cars: Which state should I register a car?

Question
I am a new driver at 23 yrs old and am about to get my first car. When I decide on what to get, I want to know which state would be better to register in. I got my license in PA, but I reside in MD for the military. Also, my home of record is Illinois, so that could be an option as well. Any help would be greatly appreciated and please include sources if you have them.

Answer
Hi Josh ...thank you for your military service. The answer is ...wherever its cheapest. The brain trust here; none of whom have lived in any of those 3 states...thinks that the answer is probably Illinois because of the other states inspection requirements which is driven by the age of the car. Beyond that the answer is I don't know with any degree of certainty which state is the best.