I have been playing 3v3 more and more and I love to play with anivia on 5v5...but no one seems to think she is good for 3s. Can someone tell me why or why not?

Anivia is fine. She can wall off teams and make it 3on 2. She has good aoe burst, and she has an extra tankiness from egg. As long as no one on your team feeds, they wont be able to burst you down unless you have horrible positioning. Anivia requires teamwork to be good.

Ive played a few games as anivia in 3v3 and she can be SO OP. if your team goes for a gank in the bottom bush early on you can completely screw the enemy team if you land your stun. i did it got an ace before minions spawned atleast 5 times.

People just don't know how to build her for TT. Anivia early game is very weak and slow and in late game requires a lot of mana to become effective. You have to use the right runes and masteries to give her an edge early game and build for late game mana/health but at the same time keep up with your ap. If you build her very good early on you can get RoA between 10-15 min and you can pretty much win every team fight with your egg late game.

I really like Anivia and play her on both TT and SR. I think she does pretty well in 3v3 games. Her stun has the potential to hit multiple enemies, she's got good AoE with her ult (as long as she has the mana to sustain it) and her wall feels even more useful on TT than on SR - there are so many narrow passages that even at low ranks it can greatly increase walking distance for opponents to get to you, and by lvl 3 it can seal most paths in the jungle. It also gives vision, which is great for checking the myriad of bushes on the map.

ive seen a few good ones. Plus i find that most "official tier lists" are all subjective towards the creator. Play who you are best with and rape face.

I think she's a pretty good hero for threes, she's got very high burst damage especially later on in the game, and as mentioned above she can wall off other team to make it 3v2 or 3v1 for short periods of time.

She is really good. That egg makes her difficult to kill and she has tons of AoE damage. Plus that wall can really wreck a team.

She is definitely good. I find that one of her most unique characteristics is her ability to leave her ult on her Nexus turret infinitely from within the fountain (bar against someone like Blitzcrank or Urgot). If your team includes many lategame champions like Nasus, she is very good at prolonging the game so that they become nearly unstoppable.

If you set her bot theres a good chance the opposing team will never see a dragon if you push at the right times