Well as a Limbo main I obviously enjoy Limbo the ability to go trough lazers and not having to worry about any of my surroundings. I usualy go into the rift to revive my team mates and regain energy (and drag along all the loot with carrier).
As of today, I'd say Limbo. Pre-rework Limbo was honestly a pain to work with sometimes, but with his rework, Limbo is one of the strong frames. Capable of taking a high priority target, such as a bombard, freezing them, and then unleashing huge amounts of damage can save a team. So can pulling a player into the rift when they're in danger.