I heard an old mix recently and noted that the reverb on a lead sounded particularly good, so I dug out the original project to see which VRoom preset (or maybe convolution IR) I'd used on it. Surprise! It wasn't VRoom at all. Bigger surprise: it turned out to be the much-maligned Pantheon.
 
Goes to show that when you find the right effect it's the right effect regardless of whether it's a "good" one or not.

I am in the Sonitus camp as well. I also like Softube's TSAR-1 in their mix bundle.

I still go back to the trusty IK CSR verbs more often than not.  Easy to dial in, lush if you want it, invisible if needed.  That said, the Sonitus verb (like all the Sonitus stuff) still finds its way in to most projects somewhere or another.

Rain
I use two of my bundled reverbs 90% of the time. When I get bored or feel lazy, I can always dig out one of the 3rd party ones. Valhalla is a long time favorite of mine.
 
So is IK's CSR, which is as close as it gets to instant gratification this side of Lexicon. In fact, CSR is probably the first thing I try if I venture down the 3rd party plugs menu. I rarely have to go any further.
 
I do love my Lexicon but I haven't connected my iLok in months now.
 
The Sonitus plugs in Sonar have always been underrated.

Just the other day in another thread I posted that I thought the CSR was becoming under-rated IMO. Glad to see some here still like it as I do. I think I bought them for $30 from someone on KVR.

When it comes to software algorithm based reverb plugins, it's hard to beat Phoenix Verb from Exponential Audio.
Michael Carnes is the man behind numerous Lexicon hardware reverbs.
 
Though it's not cheap, it's easy to justify the cost as THE one-and-only reverb plugin you'll need.
Sounds great... even on high-transient sources like drum-kit (which easily reveals inferior algorithms). 

Word.

Does anyone use any of the Native Instruments reverbs that come with Guitar Rig and/or Komplete? I must admit I haven't really explored these fully - things like Iceverb, Vintage Verb, Spring Reverb and Reflektor.

I was actually very impressed with Waves TrueVerb the other day - another which I'd had for ages without bothering to experiment with. I'd been less than happy with my Valhalla verbs on a synth sound, Breverb didn't work either but TrueVerb was ideal. Just goes to show, it's worth having a bunch at hand even if some of them only get used 5% of the time.

The RC24 and RC48 reverbs that come in Komplete Ultimate sound pretty good.
The SoftTube plugins in Komplete Ultimate (Dynamics, EQ, Reverb) all sound pretty good.
Fantastic bargain! Especially for those who don't already have favored 3rd-party plugins...

sharke
Does anyone use any of the Native Instruments reverbs that come with Guitar Rig and/or Komplete? I must admit I haven't really explored these fully - things like Iceverb, Vintage Verb, Spring Reverb and Reflektor.

I use the Vintage Verb tons! Best spring reverb I know and the plates are nice too. Reflektor is my goto for convolution because of the low latency performance. Sounds like convolution!

There are some interesting verbs in Reaktor, too.  Check the Space Master ensembles, which are similar to the highly regarded Redline reverb. 
 
Cheers,
Eddie