Ranking System
Everyone is complaining about MMR, and they should be. Queue times are horrendous for high ranking MMR, and low ranks, you get put into a sort of limbo where the match just never starts. We all have our own entitled opinions on how the MMR system should be handled, and ultimately Zenimax will be the one's who manage it; however, here's what I suggest after a LOT of thought and research.
Drop the current MMR system entirely.
Set up a battlegrounds ranking system where you can visually see your BG rank. New characters that queue are not allowed to group for ten straight matches, and during those first 10 matches on his or her new character, they're placed at the rank they should be. Players should not be allowed to group with friends in a battleground if their ranks are not 5 levels in difference from the host of the group, or simply average the group's overall rank.
If you get to a certain rank level threshole, say 40+ for this instance, level decay should occur after not actively playing for a certain period of time, dropping your character's BG rank to 40. Upon which, he or she can of course climb back up to where they were, and beyond.
Ranking should be character based as well, NOT account based. I say this because skill varies based on the class you play, you may be better on your spin to win cheese warden than you are healing your team on your templar. Ranks should be based on skill, and not all players have the same skill between each of their characters.
Yeah, I am totally suggesting do what League of Legends and Overwatch do, because they work. Whether you like those games, you have to admit, they have success with their ranking systems.
Rejoining Matches
BG's crash. A lot, at least for me. I made a topic awhile back about how I crash on my Warden to login (NOT to desktop, this isn't a PC problem or external software problem) when I use Nature's Grasp and it connects to a target who then moves to far away from me too fast for my character to catch up. I have no legitimate in-game-studio source proof of this; however, I do have a plethora of videos of me crashing to login after performing the same sequence of actions. I highly suspect there is an anti-cheat system enabled in BG's where it will try to detect speed hacks; ala, me hookshotting across the map.
When you crash, you are disallowed to rejoin and are actually penalized. You are put on a 20 minute timer, don't have access to your daily win if you were winning with your team, don't get the AP from it, and your team is upset that you crashed and they're down a man. If you can rejoin in dungeons, please allow us to rejoin matches we've crashed from. Overwatch allows this in competitive ranked matches, as should Elder Scrolls Online.
Queues
If you're in a party, only the party lead should be able to accept or decline queues. Everyone should see the countdown and have the opportunity to drop out. Too often, in fact every queue that pops, someone declines, whether intentional or just in battle and they miss it. The team lead should be notified of the queue pop like normal, whether in battle or not, and accept it for his or her team.
Additionally, If there are not 12 players available, don't pop the queue, period. I can't speak for everyone reading this; however, I am personally 100% fine waiting for a queue to pop if it means I'll start the match with 4 players. On the other hand, I am NOT okay with getting only three teammates while the other two teams run around with 4 players each. Being out-manned is a pretty big disadvantage. I am consistently running around with only 3 team mates now days, and it entirely takes the fun out of a battleground when you can't get the fullest intended experience.
Role Enforcement for Solo Queue
Roles should 150% be enforced for queuing into a battleground solo, very similar to PvE dungeons. I've had people straight up rage quit from my team because I was a healer and one other was as well. It was one of those matches where you were destined to lose because the RNG gods favored the team compositions of the other two teams, and the quitter on my team found it more viable to just quit and take the penalty rather than stick it out for last place AP. He or she knew this wasn't going to be a winning team, and was probably also going for that daily win.
Give us 4v4's and 6v6's
It would be nice to have more varieties of team-based games, outside of the gametypes (CTF, TDM, etc).
6v6 and 4v4 games.
PC-NA