I think you have the better player since Ichiro has a history of getting hurt. Markakis is much younger and has a higher upside. Ichiro will get you more SB's but that will likely be cancelled out by Markakis's RBI totals. The only thing that Ichiro has over Markakis is the fact that he's also eligible to play CF if you only have one CF. Otherwise stick with Markakis since he's hitting in one of the most productive lineups in baseball right now.