I know most call for Munich but the Vienna I have is about 6l so I figure it will be OK. I really didn't get a ton of Munich from the beers I had at oktoberfest last year but I may have been tipsy 😀.
It really just depends on what you want to make, an Oktoberfest/Märzen or a "Festbier". Not many breweries are serving Märzen at Oktoberfest, anymore, they are serving something like a high gravity Helles. As was said, somewhere between a Munic Helles and a Maibock. A local pub that carries ~8 German Oktoberfest beers in September, usually has Ayinger, which still makes an Oktoberfest, which is usually the most memorable of the lot.
Edited by Brauer, 15 July 2016 - 04:17 PM.