For reference, I putt with the Prism Proton Soft Envy and throw the Fission/Prism Proton/Prism Plasma/Eclipse.

This is the Goldilocks putter for me. Not too deep, not too shallow. Not too fast, but certainly not slow. Not overstable, but plenty stable to drive comfortably. Not too glidey, but doesn't fall out of the sky. Feels comfortable in the hands for power grip and fan/putting grip. Always goes far when I want it to, and very controllable short. If an Envy can get me to the basket, I throw it.

Every plastic gives a different flight as well, Fission is the straightest out of the box, and beats in to essentially the perfect Proxy. Neutron soft starts out very similar to other Envy's, but beats in to be the flippiest. Neutron/Cosmic Neutron/Prism Proton are very straight with a reliable bite at the end, and probably my favorite to throw. The Prism Plasma and Eclipse are a little beefier than the rest, and very durable.

If you're new, the Envy can be a great introduction to throwing putters. If you aren't, and you haven't thrown it, definitely give it a go. 

This disc is my go-to throwing putter. In beat-in fission plastic, this thing gets maybe -0.75 turn on a full rip, with the advertised fade. For more gentle shots, this disc goes dead straight until it's ready to stop moving then fades reliably. Super workable disc.

176 gram Fission Envy. Phenomenal disc. Super straight and reliable approach disc with slight fade. Can throw it hard without worrying about it turning too much. Fission plastic feels good and seems pretty durable. If you already have a Zone or similar overstable approach disc a Envy + Proxy combination should be enough to handle almost any shot within 150-200 feet of the basket. After the Buzzz, the Envy is probably my most frequently thrown disc.

This is the best disc ever made. I've been throwing the envy ever since it was released. It has been the backbone of my bag for many years. And If I were forced to play with one disc for the rest of my life it would be the envy without question. 

I bought a 174g Fission Envy hoping that the Fission plastic in the full weight would be a little more overstable than my slightly beat in Neutron and Plasma Envys. That ended up not being the case. Out of the box there was no noticeable turn like with the Electron Envy but there was also not quite as much as finish as with the other premium plastic. It flew very similar to how my older Neutron Atom flew when it was new. Very dead straight with just a tiny bit of fade at the end but also able to hold turnover lines decently well. I really like this disc but I'm not sure it will make my bag because I have other Envys that I am more comfortable with. I would recommend an Envy to anyone but as my personal preference, the Fission plastic is not right for me.