Conjurer isnt bad to level with, and you will have much more ease finding groups for dungeons later on as a healer than DPS.

I made a mistake and chose Conjurer when I really should of selected Thaumataurge (sp?!?) but went with it and hey, its not bad at all and with FFXIV you can still do the other classes... hell its a good idea to do some of them to level 10 to get some cross class skills, and if you prefer another class you simply need remember to do that new classes class quests and carry on with the main story line when your new class is at the appropriate level.

Just to let you know though, its not really worth trying to level multiple classes to 50 before leveling 1 class to 50 as you lose out on the bonus exp gain when you have a level 50 class and are leveling other classes... it easier to level other classes up when you have a level 50 class, from what I understand.