Tanking is not difficult.You can be good at any role if u put a lot of effort to learn your class in depth.As for me being an excellent DD is the hardest.Summoner is so much micromanagement imo,plus I hate the pet coz it's so annoying.Along BLM the least favorite jobs..I can only tank and heal,never liked being 100% DD and would be a scrub at it.xD