I'm not thilled with any reverbs in Sonar, to be honest, including the new Nomad Blue Verb. The Lexicon LXP suite is quite cheap, powerful, and, if you care for that sort of thing, authentic (and it sounds it). The NI/Softube reverbs are unauthorized emulations of Lexicon units and sound quite nice, IMHO.
For convolution, I like Waves' IR-L, which I got with their Platinum bundle. It has two amazing things going for it: First, it's zero-latency (can you say the same for PerfectSpace). Second, Waves gives you near 5-gb downloadable library of impulse responses, including some world-class concert halls that they captured.
For subtler things - the kind of reverb a listener only perceives subconsciously, I go to Waves RVerb. Tried and true, what can I say?