I would go with ..
Spezza - Consistent PPG average throughout his career, OTT can only get better and if Hemsky resigns we could see another dynamic duo season out of them. Michalek is too broken for Murray to think of inking him, thus my Hemsky speculation. Time will tell
Tarasenko - You know what you're getting as opposed to the many question marks surrounding the other three. He is more more ripe than the others, will get more EV/PP minutes. Playing on STL doesn't hurt either (+/-)