Moves like thought bubble really didn't strike me as too useful for PVP (except for a possible escape). The thing about powers is that they were changed in the beta to help balance them. I strongly feel that there is no best power and that a power's usefulness becomes apparent when you mix in movement and weapon abilities.
Also, some powers work better for different situations. Personally, I think the thought that there is a best power sometimes prevents people from experimenting with less used powers. When that happens, it takes longer for people to realize the full potential of those powers.
See I had a gadgets with acro that kicked but one on one (one of my best characters). I used a mixture of stealth, sticky bombs, fear gas, anesthetic, and that charge move that has an area effect. Basically, I used a mix of dominance and high burst damage to kill other players quick.
It really depends on how you play your character.
Oh and my plant character also got a tone of PVP kills in one vs one. My build was basically a wall (lol thinks of skarmory) that went for chip damage. It wouldn't be the best healer for raids but for singles PVP it was effective and annoying.
My fire, on the other hand, was good until I went from handblasters to the rifle. I think I increased my offensive and capabilities but I lost a lot of my control (which I needed to charged attacks). Even with handblasters though, I felt my gadgets user was better. And that brings me back tot he point that its all about playstyle.
you are absolutely right. I think levels plays alot into it to, as I didn't have access to many things in the gadget skill tree. I got as far as that boxing glove and turrets. Fire is useful almost immediately, but could fall off in later lvls for all I know.
I really think any power could be useful in the right setting/situation. You sort of have to develop your playstyle around it.