Tough call - a lot depends on what you have and what you think you can get because they're opposites in a lot of ways.
Crawford is never going to develop the power that everyone was thinking he would; However, last season he was injured - I'd venture he grabs a few more SBs this year.
With Markakis you're banking on him developing his power more, he's not a speedster so I really wouldn't count on the SBs.
I prefer the Rays lineup to the O's....however, I think I'd edge towards Markakis just out of worries that Crawford may have leg issues - and since that's where his value lies..
*(please note that in his short time in the MLB Markakis has slumped early on before catching fire and going nuts)