with the right gear, any character is nice. but this will cost a decent amount of fg in several cases.
the choice of your character depends on the amount of fg you are willing to invest and your aims.
you might take a look through this guide for a basic information about the game, this may influence your choice:
if your target is to well/mf in the high levels, a magician is certainly the best choice.
30 int weapon/armor + a 100+ee offensive charm and a 80+ee healing charm as mq setup will basically be enough.
check for detailed mage guides here, they will tell you how to stat and what to buy:
if your aim is to climb fast, the mage is ok, too, but you will need good low level gear in order to be competitive with melee characters in that area.
this will be quite expensive.
melee chars are fast in the early levels, but in the end casters are usually faster again unless you put a decent amount of fg into it
e.g. for life steal/mass stat gear and a high ee weapon.
rogue casters are a very nice way in between. you go melee till level 20-30 and afterwards caster. this way you combine both advantages in 1 character.
additionally, the rogue can wear all types of weapons, which makes it much cheaper than the mage.
in my opinion, in comparison to the price and outcome this is the most efficient char to climb to 71.
these are very nice guide for a rogue caster: