I'm bored, so I thought it would be a good idea to share my thoughts of every Xcelsior that we have, in order of favorite to least favorite.
2012 XD60s: Started the artic Xcelsior, they sound amazing, and they remind me of the D60's a little bit with the way the transmission sounds like on the Allison buses. The ZFs sound well too. Sad to see them leave the Bronx, plus, they are beat to shit too.
2016/2017 XN40s: They sound very unique, and usually I'd favor the artic version of these, but these sound way better, and the hydraulics go crazy on these buses too.
2015 XD60s (ZF): They ride very nice, they are possibly the smoothest sounding Xcelsiors that we have, but they are only in MTA Bus, and there's only 75, so they are usually scarce. They are VERY fast however.
2019 XD60s: The L9s are some very nice sounding engines, besides that, they are basic, unless if MTA Bus gets ZF 2019's.
2011 XD40s: Sounds VERY nice, but, just like the 2012 and 2015 XD60s, kinda scarce, since they are only in one borough, or two depots. They ride very nice though.
2017 XD60s: They sadly replaced the LFSAs in Stengel, which broke my heart, but they remind me of Voith transmission buses (personally, I don't like Voiths, but they sound good.)
2018 XN60s: Eh.......they have some loud ass backfires, but besides that, I'd rather have an XN40.
2015 XD40s:.............................................................................................................................................................GET RID OF THEM
They need work, the general consensus probably agrees that they are the worst performing/preferred Xcelsiors in the city, there are moments though, where they sound nice.