[aK13]

1. Call -- If you call, UTG+1 is very likely to raise it behind you, costing you 1 more BB to get to the river.

2. Raise -- I doubt any sane player is 3betting again here unless he has the one combination of 88 that is left, costing you 1 more BB to get to the river as well.

Thus, I like raising here, as it will likely cost us the same to get to the river, but adds a chance (almost nonexistent, but possible) chance that player behind us folds a better hand, or lets us take a free showdown.

However, if you are called, do you value bet the river if it's checked to you?

Unless the turn comes back for 2 bets, I'm probably seeing a showdown.