You come here to the Druids forums, so you have to expect people to recommend Druid over Pally in general. You should tell us what would interest you, because while both classes are very different, they are also similar as they can fill almost the same roles. The only difference is that Druid is the most hybrid of all classes in the sense that they can spec for all 4 roles (Tank, healer, MDPS, RDPS) whereas a Pally can only spec for 3 (Tank, healer, MDPS).
If you want a class just to mess around and really be able to try out *all* roles, go with the Druid. Be advised, however, that the Druid's Cat Form works much like a Rogue, so it may be redundant. You get the form at 20 and should use it til 40 where you can choose between staying Feral or going Balance. You will probably want to stay away from deep Resto for leveling unless speed is not an issue and you just want to check out the various specs.
A very brief summary (mostly in a raid environment):
Tanking: Pallies will excel at AoE tanking and still be very good for single-target while Druids will do better against single-target than AoE pulls, since our "AoE threat" is in fact a cone.
Healing: Pallies are mostly used for single-target healing and are very good and efficient at it. A Druid will also be able to single-target heal very well, but will also find that he is incredible at keeping multiple people up at the same time (known as "float healing").
MDPS: Pallies (bit rusty on this, haven't looked at the changes since WotLK) will use two-handed weapons to hit slow and strong and will use a mana bar to supply their skills. Druids, as I said above, will use an Energy system like Rogues and will have access to similar skills as well, though far from being as varied.
RDPS: Pallies can't do that. Balance Druids are to Mage pretty much what Cat Druids are to Rogues. You get spells like a Mage, but with much less variety.
Both classes have buffs and utility which I suggest you look up on your own or discover as you level.
I hope this helps a bit. Just let us know what more you would want to know, as there are too many differences between the classes to list them.
Edit:
Quote:
The thing i really dislike in Pals is the necessity to keep an eye on suitable buffs on everyone in the party...
Yeah, I disliked that too. You have to sync with other Pallies to make sure you don't override anyone's buff. To be fair, though, there are less buffs now so it's really not that hard. Just a pain that the buffs have a shorter duration than most other buffs.
Edited, Feb 25th 2009 12:11pm by Selverein