Hedman is nowhere near "nasty" thats for sure, trust me, Lightning fans such as myself have been dying for him to play meaner/tougher. Potentially, Hedman has a higher offensive ceiling than Myers, although theres no guarantee he reaches it. Myers is the "safer" of the two options. Probably add Erik Gudbranson and Jared Cowen to this list of young "big defenseman" would help a bunch with PIMs, hits and blks, both of which capable of producing 20-25 points annually.
Hes a little ways down the road, but the Jets 2012 1st round pick Jacob Trouba is worth an honorable mention. And another guy not as well known is Nashville prospect Mattias Ekholm.
Stamkos was asked today in Tampa how he can top last season:
"Well, get into the playoffs. That's the big key and that's our goal here."
Follow me on Twitter @thehockeyhitman