I think a combination of verbs might be the best option for software.
I know you said you dont liek the Waves verbs, but oyu may want to try a combo of Trueverb and Ren Verb. Using Trueverb to create early reflection data and shape a "stage" sound and use Ren Verb to get the "trail". This helps you keep a defined sound, instead of using just Ren verb alone, which will jsut muddy up the sound, or just true verb alone which sounds like poo poo in terms of long trails.
I personally haven't found a software verb I'm really fond of. I am in favor of convolution, but its, right now, processor hungry in most apps (except the new samplitude, I hear). Its all bound to change this year tho, with new software and such coming out soon, someone will add better reverb options for us.
I still think your best bet is to route out of Cubase into a hardware verb, then back in, if you're looking for a master verb. Even the Roland verbs in the VS systems are pretty good.
If you're not looking for this reverb to be realtime for playback, you may want to look into Acoustic Mirror, from sonic foundry, with the right set of impulses, you can go far with it. Its a similar conept to "altiverb". Its just that its processor AND buffer hungry, so cubase may have problems with it (I dont know about SX, it might be fine)