I have a level 70 guardian… those things are OP!
I can easily do a group event by myself, but it takes ages to finish due to the low damage output compared with other classes. If you like being able to take damage and still stand, the healing options and damage mitigation skills a guardian offers is outstanding.
As for warrior, I have a few guildies who have chosen that profession. The damage they do is insane. I can’t even compare with the crits they pull of! However, there must be a downside of which I am not aware. They might be more squishy or less able to heal, I don’t quite know.