I've played almost every agent competitively now. I can safely say Breach, Astra and Viper are my least favourite agents to play.

Breach - His concussion and that explody ability are super easy to avoid. Amazing flash though.

Viper - Managing the toxin meter for the orb and the wall gives me major anxiety. Also pressure from the team to do line ups.

Astra - Nope. Just leaving my body to put stuff anywhere is powerful, but makes me super anxious about my location awareness if that makes sense. Also the ult is useless imo. Only blocks bullets but allows abilities ??!??!!

Favourite agents to play right now are Sova, KAY/O and Skye

Sova - A great agent to play for beginners. Don't be pressured to practice lineups, with enough game knowledge, you can pretty much stand anywhere and shoot your arrows to any position, no memorizing lineups required.

KAY/O - His knife is easily the best ability in the game. I can turn off enemy abilities AND reveal their positions? Amazing. Plus he has the simplest to use flash in the game. Super easy to pop flash. His molly I haven't found a good use for other than as a way to deny entry to a site. And his ultimate is a good deterrent.

Skye - Amazing flash, good dog and the group heal is better than sage heal imo cause you can heal more than one person. Great ult (but make sure 2 of the enemy team players are already dead before using it for max efficiency)