Depends on your play style. Me personally, if you're good as a defender or striker Titan with suppression/flash grenades respectively, then the incendiary grenade is right up your alley. Avoid swarm grenades, they're....mediocre at best, even after the buff. The alternative is to use trip mines. They're not quite as powerful as they used to be, but they're still great at taking out enemies who have retreated behind cover to regenerate their HP. Pair this with a max Disc build and the Young Ahamkara's spine exotic gauntlets and you'll have trip mines for days! For my play style, I prefer incendiary, since I can use them offensively or defensively. The dot that they leave after detonating on a target helps me track them for a few seconds if they're behind cover, and I can bank them around corners to get at enemies that I would likely have to expose myself to otherwise. So for the more aggressive play style, I would say incendiary grenades are better. I'd play around with them in patrol for a while until you can place them where you want them to go (use a weapon with grenadier to help reduce the down time between grenades as much as possible) As for trip mines, I find they're best used reactively personally. Place them in areas where you suspect the enemy might move to, ideally in a location that they must walk into the mine (not past it). Trip mines have a slight delay before detonating, so I found the most success with placing them in such a manner that forces the enemy player to come directly at it where they have little ways to get out of the blast radius. Placing it perpendicular to a doorway leaves open the possibility that the enemy player will simply sprint past it, avoiding the majority if not all of the damage.

Use the first one (I think) it's the burn damage over time and throw them at the adds spawning from the doors. Or if you can entice a few of them to chase you drop one when you have them funnelled.