Druids and warriors are both great. Druids are easier to level, obviously can do many things warriors cannot, and warriors get handed all kinds of gear like candy in higher level play, while everyone else picks leftovers to make their spec work that may not be entirely aligned with tier sets.
Druids have tanked pretty much everything, although there are many limitations that keep them from always being the best choice.
One primary weakness is the inability to break fear. You could have the pvp trinket, but you’ll likely get one whole use out of it. Alliance Druids get the benefit of fear ward from dwarf priests, obviously. And horde would have to hope that he gets a tremor totem proc.
Another weakness that is universal to Druids is that they can’t use many items in form, nor can they pot of any kind. There are tactics around this, but things like armor pots are locked into pre-pull for many fights as it’s dangerous to pop out of form while tanking (although not impossible).
Another Druid limitation is some boss fights just won’t work well, and are best for warriors. Such as a fast attacking boss has the potential to crush you very quickly if you are unlucky.