EQ:FabFilter Pro Q2 and sometimes the Waves Pultecs for flavor. I don't think I've had another EQ open in a year now that I think of it.
Compression: FabFilter Pro C2, Waves RVox, Waves Fairchild, Cakewalk CA2A(!), Waves Kramer Pie, Native Instruments Solid Series bus comp (SSL type). I experiment with those a lot more.
Reverb: ValhallaDSP, Waves IR1, recently FabFilter Pro R. Sometimes something like RVerb or the reverb from the BlueTubes bundle when I need something lo fi sounding.
Delay: I guess I'm pretty basic with delays, I really like Waves H Delay and sometimes SuperTap. Was interested to hear about Tritik tkdelay, I'll check that out. Have used and liked Sound toys Echoboy, but I can't bring myself to get into the iLok thing. I used Sonitus a lot before H Delay and it did great for me, just really annoying to automate because you can't do left and right simultaneously (link is ignored when automating).
Modulation: I'll usually try lots because they can sound so different on different material. The BlueTubes chorus can be quite nice, I also try all pedals from my amp sims. Waves Enigma and MetaFlanger are cool.
Distortion/Saturation: Klanghelm SDRR often hits the spot, I recommend it. I love FabFilter Saturn. Recently got Trash 2 in a bundle and managed to find a use for it straight away. Waves Kramer Master Tape sometimes. And Waves NLS. I honestly don't really use it religiously like a console where I insert it on every track and bus, but it can give a nice interesting flavor on individual tracks and some of the variations between the modeled channel strips are actually quite big, it's worth stepping through them. I haven't had it for very long but I've found it much more useful than the Cake included console sims so far.
Multiband: FabFilter Pro MB takes care of most stuff. I guess Saturn counts as multiband. Sometimes Waves Vitamin if a source is really lacking something. Often I find I have to dial it back after I've set it though.
Guitar: SGear 2 mostly. I have a bunch of others but I guess the point of the thread is "where do you usually find yourself" and I often start and end up there.
Bass: Waves CLA Bass. I can't figure out what it does all the time but it often does exactly what I didn't know I needed. I'm not a fan of "black box" plugins but I'll admit I often struggle with bass so it really helps. Waves Bass Rider is a staple too.
Mastering: Ozone and Waves L2 for quick.
Special: Waves S1, Vocal Rider, Melodyne
If anything this thread shows that you can get decent results almost regardless of the tools.
But it might also end up as a shopping list :)
Honestly I don't look at it as wasted money, having way more plugins than I use most of the time. For me, I learn a lot for instance about the sound and functionality of "compressor A" because I also have "B through Z" to compare to. It makes me a lot surer that I picked the right one, and it helps me decide the next time which one might work well for a given source. And sometimes something you almost never use turns out to be the solution to a specific thing.