So I don't use indicators much at all any more, except as sighters for sub #20 dries (just can't see those tiny things anymore) but I have a couple waters where I'll still use them.
So, at this point I pretty much solely use NZ strike indicator wool, mostly because of how easily it casts, but also because of its stealthy properties. But on this one piece of water I use it because I can shape the wool into a 4-5 inch long 'plume' or feather shape, which allows me to fish a 18 ft. leader to a heavy nymph which must be cast 40-50 feet, and then 'walked' or crawled along the bottom. The end of the wool plume will either stick up or lay flat on the surface, and doesn't interfere with my ability to make a long cast. And it will just barely float all of that leader/tippet and tunghead bug. Finally, if a fish does rise off the bottom and whacks my fly, the wool is so light it will transmit that strike on the long drop.
Wool also works really well with really light stealthy nymph rigs, such as commonly used on most of the Juan.
The other indicator I sometimes still use is a slip strike indicator, for fast waters, like the Ferry. At the Ferry you need a 14-17 foot rig, with a couple beadhead zebra midges or the like, and a fairly large split shot. With a fast current, you just have to have a high floating bobber, but trying to land a fish with a leader that's almost twice as long as your rod in that current is a pain. The slip strike bobber allows the bobber to slide freely up and down the leader after the hookset, so no having to grab the leader and hand-walk the fish in then grab your net and try to scoop your fish.
I think the exact brand I used to buy has gone under, but I've seen several versions that probably would work just as well. Rogue River is an example.
