I have a similar setup as you do.
war, enc, cleric, wiz, and when I don't have guildees in the group, my mercs are wiz/wiz hands down.
I have no idea where people get this idea that wiz mercs go OOM. Have never seen my wiz mercs go oom unless it was apprentice. If you set your wiz merc to balanced, he's not going oom ever.
My war is pretty beefy and I have set my wiz merc on burn. The problem there is unless you configure your holys to include triggering the merc on or off, they are going to die. Especially if you are fighting mobs that summon. Burns on merc make them attack at 100% or damn close to it, so if you don't grab aggro right away they are getting face punched immediately.
You are rocking an enchanter and enchanters compliment wizard nicely, so all those AAs that you have that improve spell damage are a no brainer with wiz mercs. Chromatic haze, illusions, dicho, mindsunder, etc.
You did not state what your latest expansion was, however IF you are doing fine in EoK, you will gain 2% per kill on mercenary AAs, which makes them accumulate pretty quickly. <--this will increase with the two week anniversary experience bonus.
Enc + wiz = marriage made in heaven
Get two wiz mercs, put them on balanced, and live a happy EQ life.
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One other thing I wanted to add is that you can always use a different style merc to benefit you short term but use the AA for the merc you plan to use in the long run.
For example, if you do have EoK and it's a little tough for you or you do just OK there, You can use a cleric merc as back up to keep your tank up all while getting banked AA and then spending then on the melee/caster AAs.
Then as you get you beef up your actual characters through AA and gear you can swap out to the dps mercs.