Really depends on what youre looking for in your vocal design. In my opinion all you really NEED for vocal production is EQ and compression. Reverb and delay can help glue your vocals into a mix nicely, I use primarily Valhalla suite or Eventide suite effects for that (Valhalla Vintageverb is invaluable in my work flow). Beyond that the world is your oyster.
Some more out there effects that I can recommend specifically are: Pitchwheel and Halftime for pitch effects Tverb is a great spatial reverb Freakshow Industries are great WTF plugins also I prefer vintage table emulations over dis/overdrive effects for adding grit.