I would check as you still have everyone to play behind you. Too many hands can have you beat. JJ not optional UTG to play strong unless you have somewhere too go.
Your stack size and the effective stack size of anyone who can cover you.
The stage at which you are at in the tournament.
The table images and calling ranges of others at the table.
Your previous calling range and table image prior to this decision.
JJ UTG is obviously worth playing and more often than not - a small raise is optimal as a play to see where you are - the only caution is here, anyone playing less of a hand but hitting the flop is likely to bet out and chase a set or better, isolating player numbers is key here and again any reraise should be judge on its merit - the deeper into tourneys you go - the likelihood of players jamming AK against any raise is increased as is any pair.
Most of the scenarios I would go all in, but it would depend on how early or late the MTT is, cash game I would 3bet, see how the table responds and see the flop, if we see an overcard DONT overplay...
Well most of the times ill go with a 2 bet, expecting someone to go 4 bet or 3 bet. Even if they dont, usually around 3 to 4 guys see the flop, which is good in payout.