I've been using a homing slag mirv with a 0 fuse time. Amazing stuff.
Also started using a fire burst on a new character, those are good, too. They let you trap a corridor or doorway, for example, and all you have to do is stand on one side while enemies rush in and die.
Don't worry; your manhood will be safe even if one of the PCs in the next game wears pink. Get over it. - EvenSpoonier
I had been using a high DoT Corrosive one for the longest time since they pretty much dissolved anything with full HP I threw it out. Now I use Longbow, high-damage slags. Between those & my rocket launcher, big targets die fairly fast.
Singularity Slag Grenades. not only is the slag effect great when my turret is on cooldown, but the utility they give is astonising. throw one at one of those ion loaders and it will pull them and drop their shield.