It all depends on your play style. If you Run & Gun, the Jetpack would be more efficient in surprising opponents in the middle of a gunfight. If you play tactically with your friends, the regen field would be a better choice as it would heal your whole squad. The Hardlight Shield is also effective in teamplay, as you can use it to be a distraction and your buddies can come in and sweep.
I love the Thrust Pack. It really is useful when you're trying to escape enemies who are chasing you. However, I mainly use it to boost myself behind an enemy who is tailing me: it really throws them off. --- Mafia vs. Irish Mob (BROTHERHOOD series) http://www.youtube.com/watch?v=4C-ogMPoBRk
Jet pack is pretty dope but you have to use it right.
I see people jet pack just because they can. That's bad, and you'll have the entire enemy team crossing you every time.
If you use it as more of an evasion and mobility tool to get to places quickly that you normally wouldn't be able to, it's very effective.
Ex. You're in a 1v1 and you're dancing around with your opponent. They take cover. Rather than having to blitz them and take a risk, you just JP for an angle and take them down. --- "It's like people using the internet have never heard of the internet." - SadHillShowdown Gamefaqs member