I have not demo'd R2 or Phoenix Verb yet, don't have the resources to purchase either one just now, and running the trial would likely make do something foolish<G>!
But I will tell you that Excalibur is on a par with not just some of my favorite UAD plugins, but also my PCM-80.
What I like about Excalibur:
1) it covers a LOT of sonic turf, everything from gentle chorus to bizarre sound design
2) the user interface is laid out logically, and I can find everything I need
3) I was able to use it, and create my own patches without opening the manual... been a while since I could say that, heck, I can't say that about the PCM-80!
4) the preset library probably has a preset you can use, or use as a starting point, and the library browser works nicely.
5) the sound quality - and let's be honest, this is what makes or breaks any audio tool. The sound quality is on a par with any plug-in I've ever used, and my hardware. It does not sound exactly like the UA Cooper Time Cube (although I've been trying!), nor does it sound exactly like the PCM-80, but it has that same vibe, if that makes sense. It just sounds good (or weird, or downright bad, depending on your objective).
Can't think of a single complaint.
Except that of course now I am (more) curious about his reverb plug-ins!