Re:
The world is your oyster really, depends on what you prefer looks wise.
I'm sure most replies would be kore or syncros, as this seems to be what most older zaskars get built with, and nothing wrong with them either imho. What seat post do you have? Want to match it?
Lots of other options to choose from including, but not limited to thomson, hope, use, race face, titec etc. I hear good things about the quality of syntace. Controltech are also good and more retro.