I guess I'll just post somethings I think are important for own personal enjoyment.
Class diversity: This has been talked about extensively over the last few pages, and I agree with most people. Clerics SHOULD be the best healers, Warriors the best tanks, etc. I played a Beastlord, and I really enjoyed being able to slow, do very good DPS, and even tank once I had enough AAs. Fuck, I used to pull for our PoE groups and shit. Ports are great imo, and spires and boats should return. I really hated the flight system in WoW, and the summoning stone was so fucking stupid. I still remember waiting for my first spire port and getting the item in my inventory. Enjoyed that much more than fucking just flying around, and it seems to have more appeal in a fantasy setting imo.
"Old" mechanics: I really miss things like slowing. I thought it was such a cool thing, personally. Having a slow and not having a slow completely changed the dynamics of the group and how to approach mobs. Shit like this really needs to be reimplemented into modern MMOs. Pulling was a fun mechanic imo, but I do see the problem people are talking about. I'm certain there's a way to fix it, but I personally don't know it lol.
OT/DT: Vanguard were fucking geniuses for this, and I really hope it makes it into Pantheon. Being able to heal as a Shaman while doing damage was an amazing feeling and made healing not as boring. I enjoyed healing in WoW, I won't lie, but Vanguard was easily the best healing experience I've had so far, aside from that fucking bugged isle that did 25% damage to everyone no matter what gear or level you were. I don't remember the name, but fuck you Brad for that shit, it ruined my senior year of high school.
I also hope the KS will have a tier allowing alpha/beta access. I'd really like to participate in the development of this game, finding bugs, discussing balance, talking about the world, etc. I know Brad talked about an extensive beta session, I'm hoping most of us will be allowed access to it considering the community we're talking about here.