Before I answer, I feel I have to qualify my answer.
I am the sort who:
* doesn't feel all the roles need to be filled
* doesn't encourage detailed player conversations about what types of characters they are going to make for the game
These two factors allow for more diversity on party composition and tactics -- making every group more unique (for me). Though, I also do not run published adventures as is, so I have a lot tweaked for the party composition.
I also abhor rolling dice as a DM. I roll way too many already and the thought of rolling more irks me - so a DMPC would make me a sad DM. So the NPCs remain as plot/story characters, not adventuring companions whenever possible.
Having said all that... *if* I _had_ to have a DMPC in the group because a gun was being put to my first-born's head, then I would go with leader or defender.
* Leaders offer more support to characters. (Of the leaders, I'd go with warlord, that offers less powers and options to keep track of since clerics have the power divinity things which adds a couple more, and as a DM you have enough options and powers to keep track of to begin with)
* Defenders can act as meat shields to soak damage while the PCs run around doing the nifty abilities that make them feel all special inside. (Of the defenders, I'd go with fighter -- it has the simplest of the "mark" abilities, which in turn means less for you to keep track of over all. Maybe paladin if you feel there should be a little more healing than is already covered)
I would _not_ choose controllers because they have the potential to hit more targets which would outshine the PCs. Similarly, I would _not_ choose strikers because they have the potential to damage more to a single target, again, outshining any other PC.