I, too, am utterly biased.
I really wish Alistair were a bit more deliberate in his craziness. Wouldn't it be great if the awkward thing was a front to get young ladies to fall for him? Oh, crap.
I broke it.
Zev is really perfect for most of my characters, as they tend to be seeking someone as broken as they are--most of the time I play dwarves, and there's no way around some level of either super jadedness or trauma or deceit or, well, you know...
At least the Cousland origin has a fairly straightforward enemy. Even with Bhelen, you don't really get to be the poor distressed and wronged 'good guy' in any case, you're either easily manipulated and won't give Bhelen the credit he deserves for playing Orzammarian politics like a true king would, or you are flat-out a kinslayer, you know, regardless of whether it was a set-up.
Here I am rambling about origin stories

The point is that Zevran is generally a perfect fit for the wackiness I concoct based on what BioWare's staff has given me.
Except for the one time I wasn't completely crushed by an Alistair-related ending, and my Brosca who is Leliana's ~forever~~~.