Hey Josko, no fair throwing in another species.
I see your point about stalking bonefish, however, I've found that fishing for tarpon recently in the Florida flats, and in talking to those who have recently, the tarpon have gotten a lot like bonefish. It's become much more demanding. A perfect cast is no longer a guarantee of a hookup. Presentation has to be spot on, and the ability to read the tarpon has become paramount if you want to do well. To each their own - that was the point of the posted question to see which aspect you like best.
As far as Marlin, I do want to pursue them one day but in some ways not as much fun - as Andy Mill said, you tease them up and after they're excited, it's pretty much flop your fly out there and it's a guaranteed hookup. Not to say I don't want to experience the fight as well - I most certainly do. But I do want the combined aspect of casting/presentation with a great fight. For me the bonefish do demand good stalking skills, but the fight it completely anticlimatic for me. I don't fault anyone who prefers the bonefish - I know a lot of guys who don't care to fight big fish either - plenty of room for all of us to enjoy fishing the way we want. Neither way is right or wrong, just personal preference.
Now time to go pack - leaving for Key West tomorrow morning. Time to jump some 'poons.