You do realize this thread was started in March of last year right? That is why it says X1a. It just seems to have been revived.
My two cents:
For value you just cannot beat ValhallaRoom as several have said. In fact, ALL of the Valhalla plugs are just amazing. I got Shimmer and have been channeling my inner Brian Eno. UberMod is also just great.
For those of you that have no issue with the iLok (please....let's not start that war here) I can't say enough great things about Softube's TSAR-1. That is the big brother of TSAR-1R which comes in the Softube mix bundle that Cakewalk sells. That whole bundle is a GREAT deal by the way IMHO. If I could only use 1 reverb in a project it would be TSAR-1. Not cheap though if bought standalone. TSAR-1R is really good also just not as flexible.
If you want to get wild effects well beyond standard reverb then Fabfilter's Timeless 2 is just amazing. More along the lines of reverb/delay.
Ken