Starting a new toon what opinons on Spriest and aff lock.

Played Wow for a long time and have mainly played TBC SHp. I leveled a mage on icecrown years ago and hated the playstyle. In recent times I've played priest (disc on retail BFA and shadow on tbc pservers including outland). really want to level and get into some max-level dungs, raiding and PVP . I really love shadow in T4 TBC being my favorite class/spec in any expansion next to disc in the most recent BFA expansion.

I love to play caster DOT classes and top the meters with very hard complex rotations. However, I love to play support and healer classes which I heard Spr isn't a very good support, DPS, or has a fun complex rotation. I also love to PVP when I'm not grinding PVE. I will add that usually on Pservers I tend to only play DPS and not healers. I really haven't played WOTLK too much and thays why I'm asking this. Any feedback would be great.