The comparison is a bit difficult because they play in such different leagues. IMO, Tukonen will come to the NHL before Setoguchi because he has experience playing with men in both Finland and now in the AHL. Admitedly, I have seen Setoguchi more times than Tukonen, and while I have caught Tukonen with the Monarchs, I have only seen tapes of Tukonen's time in Finland. Already, he has a more polished and mature skillset. Setoguchi and Tukonen are both average defensively, although I would give the slight edge to Setoguchi. I think Tukonen could have used some more time in Finland, however.
Tukonen is much more consistent, and uses his 6'2 frame very effectively along the boards. He is not afraid to be physical, either. His only mistake in the offensive zone is that he tries to do too much. Since being drafted, Tukonen has progressed in his offensive prowess, but has not taken any visible steps to correct the flaws in his game. If he irons out the few kinks in his game, he could be a great second-line forward. I think he lacks the top-end talent to play on the first line.
Setoguchi is more well-rounded offensively; he is a better playmaker. Though small, he possesses a mean streak, and is very Mike Ricci-esque on the ice with his grittiness. Very tough mentally, Setoguchi is a game breaker. Unlike Tukonen, Setoguchi has worked on his flaws; he has gained muscle, plays more physical, and is a more dedicated backchecker than when he was drafted. No doubt, San Jose told him to make changes, and he did. Like Tukonen, he has a tendency to do too much on the ice; Setoguchi often overestimates his stickhandling skills, and he still has to learn to pick his spots offensively. When he is at his best, Setoguchi more than justifies his draft position, and looks like he could be a bona-fide top line winger. When slumping, he does not look like a first round pick. So unlike Tukonen, who is a safe bet to at least play on the third line, Setoguchi has a distinct chance of never cracking an NHL roster.