This subject was discussed in another thread recently. My bus is an International/BlueBird that's about 25' long and weighs 14,180 pounds in its more-or-less as built state. Searching in the states, you'll find 4 basic configurations.
Type A, also known as a "Cutaway" style bus. Ford and GM/Chevy are popular chassis to base these on, similar to "Airport Shuttle" style buses.
Type B, not common "Bread Truck" style buses. Ford and GM made chassis for these over the years, don't see too many around.
Type C, common "Dog Nose" style bus. Very common and chassis by Ford, GM, International, and Freightliner were used. Blue Bird also began building their own chassis (I forget when). The IH/Thomas(?) "Vista" style bus could be listed under this category.
And finally, the Type D "Flat Front" bus, available in front or rear engine setups. Same manufacturers as the Type C for the most part. There were a few odd builders who produced Type D buses for city/transit/shuttle usage that I did not list.
As for "which is best for you" is like asking which is better, Honda or Toyota. Much of it comes to personal preference. You did mention short buses, so it's unlikely you'll find a Type D Flat Front bus shorter than about 25-28 feet. Research carefully any bus you consider, especially those newer than 2004 since diesel emissions laws came into effect at that time and the emissions engines were nightmares in some cases. Feel free to post questions about prospective buses, engines and such here for others to offer feedback on. Oh, and when asking about the transmission, *DO NOT* just accept "Allison automatic" as an answer, you want to ask what specific model of Allison a bus might have. The AT545 isn't a bad transmission for city stop and go driving, but it leaves much to be desired for any amount of cruising especially in any hills or mountains. Pretty much any other Allison is OK for longer trips.