I've played Rigs, the block puzzle game (I forget the name, but the developer was so nice to chat with!) at PSX and Harmonix Music VR at E3 2015.
I also tried Eve Valkyrie at Pax South on a rift.
Between PSVR and the Rift, I honestly couldnt feel a difference in terms of immersion, but the PSVR's resolution/screen made things like grainy for a bit until you got really immersed. The PSVR felt MUCH more comfortable, especially the final unit which was at PSX.
Honestly, even though I do not play shooters and will likely not be purchasing it, it was Rigs that sold me on PSVR. It feels like a full fledged 60 dollar title, the grpahical fidelity is amazing, and VR actually enhanced the experience. Plus, it's super fun. I'll def be picking up the cube puzzle game because I expect it to be a 10-20 dollar title, and am considering Harmonix VR as well, where you just really sit and chill to music (and can import your own tracks!)
Since VR demos are about to be set up across the country, you are about to hear way more impressions