Guild wars 1. Its a skillbar mmorpg, 1 time purchase for $10. Its back in active development by a small team.

You get a primary profession like warrior and a secondary one like ranger, monk that can be swapped at any outpost. This allows you to get access to a much wider array of skils to build for the situation.

Each profession has a primary stat so you dont have warrior/monks out healing monks because they dont have the devine favour stat.

But there is still a ton of build diversity and role diversity.