I like them! They're a nice change of pace. Plus, it's probably a good way to get some early training for Rogue Core.
Honestly, even the Stalker is pretty cool; it's very satisfying to ping.
The one I hate is the sceptic spreader. This one is so dangerous.
For driller: Sticky flames for sure, especially on swarmaggedon warnings
Unstable Containment Field is fun too, though hard to master
Also the shotgun effect on the goo cannon. Helps a lot with range.
For scout: Focused shot, even though it's dangerous on higher haz
The no recoil one on the submachine gun
And yeah Special Powder of course