dicuss

melee

Melee if you don't mind relying on catas to level, caster if you want to be able to solo and don't mind the leveling going a little slower.

melee

the path you choose depends on your current gear and your financial means to a large extent in my view.
if you already have a decent melee setup your monk can use, you should go melee instead of changing the whole setup.
if you have charms and armors already but lack weapons, its not that problematic as ee staffs arent very expensive.

but i made the experience as well that im much faster in catacombs with a melee setup, solo wasnt that fast in the higher levels any more.
so if you are rather the solo player, maybe go for casting. you are pretty independent here and can still heal in catacombs
( although your mana pool will not reach the size of a mage's one certainly )

same for casting. if you have a nice caster setup already e.g. from your weller you can simply stick to casting.
if you had a mage before, you can basically use the same setup on monk, too.
but the early levels might get hard as caster because monks will start with less mana.
so maybe going melee the first levels and switching your setup to caster later on in the middle levels once your mana pool is big enough can help.

personally i made good experiences with going hybrid

you must prepare for the case when you can NOT find a good cata game.

in arena i've had very bad experience in robe melee (ninja) at lvl65+ while caster build had no problem except lower max mana + longer regen time.
my choice is hybrid caster (like rogue). full int stats, play as melee till 30 and the rest as caster.