I stopped using UV/Haze filters a long time ago in favor of less crap in front of lens. However sometimes they are still useful; I'm thinking near water spray they can act as a buffer over the lens if you quickly want to set up, take it off, and shoot, the spray is all on the filter and not your lens. Also I have dropped a lens once that did get saved by the fact that the UV filter cracked
But instead I am just more careful these days, haha.
For my GND's I have 4 various Singh-Ray 4x6 rectangular GND's (these go with the Lee filter holder) but I am not happy with them, due to the heavy magenta cast they create when stacked. I used to think it was cool when I first got them and over time just grew tired of the cast. It's really hard / nearly impossible to correct it in PP, also.
I use a Fotodiox 155mm CPL with my TS-E 17 but that is a special lens and special filter for it, as well as a 6x9" Fotodiox 0.9 GND filter that stacks over the CPL. It has a very minor magenta cast, and I imagine that if I had 2 or 3 of these, the effect would be much worse.
I still have a bunch of filters from my film days that have become obsolete with digital photography, like FL-D filters, which are mostly just relics for display at this point
Generally speaking, I find myself using the CPL and GND's more than anything else. I also like ND filters which help with contrast and to lower shutter speeds when there is a lot of light out.
I do want to get a 10-stop ND filter for that silky-smooth water effect, and for long exposures in general during daylight and/or ample golden hour light.
And, I still want to find a brand of square/rectangular GND filters that don't produce a magenta cast. That would be awesome.