The Nova LFS all the way. I moved from a city that uses the New Flyer series exclusively (Philadelphia) and not only were they rather unappealing to the eye they were also VERY uncomfortable to ride as the seats were small and hard, plus the window placements were too high and the floor too low (though they were the first LF buses that I rode on a nearly daily basis). The hybrid versions (diesel+battery) are extremely quiet, though.
*Apparently SEPTA knows it, because from checking SEPTA's site, they're replacing their old Neoplan articulated fleet with articulated Nova LFS buses, and some of their older New Flyers with the non-articulated version of the Nova Bus. Huh...
Regarding the NABIs, I have a personal grudge against North American Bus Industries. New Jersey bought 1,174 NABI 46-inchers to replace their 20+ year old Flxible fleet, and there were constant problems with them ever since - the doors would pop off, the engines would cut out, they leaked when it rained or when the air conditioning was on, and the PA systems would cut out. I can't count how many times passengers (myself included) had to leave the buses when they broke down during the first three years of service (from 2009). Even worse, NABI wouldn't give NJT favorable warranties on them - more evidence that they built them as quickly and as cheaply as possible regardless of safety so they could pocket the State's and the Fed's cash.
NJ can't run low-floor buses due to predominately hilly terrain, but they had better options than NABI as a high-floor vehicle of choice...
The Nova Bus though, served both cities well throughout the years. The engines on the 1980s and 1990s series were REALLY loud (since I was a kid I loved the Novas but I hated their engines) , but they were fun to ride with better seats and tinted windows, plus they were descendants of the "fishbowl" look. The current and upcoming models look REALLY classy.
It's no surprise that the Nova option is winning by a landslide. Let's hope that should CO put them in the game, their attributes will reflect their real-world counterparts fairly (speed, service, etc.).