For Vox plugins I begin with Izotope Nectar Elements, I can generally get what I want with that as a starter, it's got a load of good options in there, including delay and verb.
For reverb I use Variverb Pro (came as part of my DAW),
http://www.musicradar.com/reviews/tech/magix-variverb-pro-23082sometimes a Lexicon MPX1 outboard FX unit (I know not a plugin but has very good vox reverb)
http://www.musiciansfriend.com/pro-audio/lexicon-mpx-1-stereo-processorExternal fx units are now getting cheaper, and the quality really is superb, just a bit of faff using them in a DAW, AND it provides many more fx's so you do get a big bang for your buck, and it's not the traditional guitar focused fx unit.
I know neither of these are free, nor particularly cheap, there are many more that are more expensive, trying to find that price/performance sweet spot is always difficult, and these do the job such that I don't feel like I need to spend any more wallop.
I often setup a few aux busses with variverb pro, each with a different verb setting, and send a track to each one, thus relieving the need for multiple verb plugins, and it spares the CPU.
Hope this helps.
cpm