Actually, if you're trying to replicate Batman, Avenger is -exactly- what you want. Stealth? Yes. Zipping around the field? Yes. An unstoppable force that will destoy his opposition. Yes.
Go Warlord tho. They're seriously awesome.
Actually I know very little about both avenger and warlords. Of course I can read the books, but my experience from the fighter told me we know nothing until we start actually playing.
Took me 3 months to fully underestand the Combat Challenge x Combat Superiority diferences, considering builds, feats etc.
So if I would go warlord I was considering a balanced one, something like this:
S - 18
C - 10
D - 10
I - 14
W - 10
C - 14
Maybe a resorcefull or tactical one. Admitelly I am lost here. If I go Hector Style I will probably combine Spears/Javeling/swords and a light shield. I have noticed some powers that require heavy throw weapons, but I am still clueless about warlord builds.
I also admit that the Spear as a Simple Weapon annoys me a bit.