Probably Lincoln. Martinez is very popular and has a solid political base in the district, unlike Garcia.
But he also has the baggage from the trial. His political base is quite similar to Harry Mitchell's in AZ-05. The main differences are that AZ-05 was a little less Republican than FL-21 and Mitchell's home base was diluted by other suburbs where his name ID was much lower. The scandal factor worked in Mitchell's favor; in FL-21, it may work against the Democratic challenger.
Garcia's background offers little fodder for attack ads, which is immensely helpful to a challenger.
I always think of the AZ-05 race when I think of FL-21. To say that there was a scandal factor in AZ-05 is really pushing it. Hayworth may have had some vague ties to Abrahamoff, but it was nothing like in CA-11, FL-16, or PA-10. Still, Mitchell winning that district was a huge surprise to me on election night.