As I have said before, there is no one bus that is perfect for everyone. As in one size does not fit all.
In regards to school buses, currently the prices are way down. $3K+ for a TC2000 with wet brakes is a bit on the high side IMHO. Check out
http://www.harlowsbussales.com/inventory/. They have quite an inventory and the prices reflect that fact.
The 5.9/ISB that is used in many Freightliner, Blue Bird, and Thomas buses is almost identical to the engine in Dodge pick-ups. They do suffer from the dreaded killer dowel pin syndrome. But it has usually been dealt with by the time the bus is surplussed.
The 5.9/ISB is what it is. It is relatively easy on fuel but it really lacks the HP if you are wanting to cruise at highway speeds or spend time in the high mountains. The 8.3/ISC or the DT466 may have similar HP and torque stats but they will climb the hills and cruise much better. Installing chips and other aftermarket enhancers can solve some of those problems but then you will start to have overheating problems. There is no free lunch.
If you are wanting to build a back porch then you are pretty much locked into a front engine bus. The down side of the foward control buses is the engine is right next to you. Read that as noisy, particularly if it is a Cat 3208. A conventional body bus gets the noise outside of the passenger compartment and you really don't lose that much in interior space.
You will want to stay away from the wet brakes. They are not as large as the air brakes in similarly equipped buses and require a lot more attention than air brakes. It is exacerbated if the bus isn't driven on a regular basis. Since brake fluid is hydroscopic you end up with rust in the system that ruins seals. Or worse, lowers the boiling point to where you boil your brakes on a downgrade.
At the end of the day, it all comes down to what you want and what will fit your needs.
I have some words of advice for you.
First, don't fall in love with any particular bus until it is in your driveway with our name on the title.
Second, spending more for a bus that is clean with no rust will save you a lot of time and $$$ in the long run.
Third, the power package is the most expensive part of the bus. Spending more for a good power package will save you many thousands of $$$ down the road. Upgrading power packages or replacing dead engines or transmissions in a vehicle the size of a bus is not cheap. $6K, not including R&R, for a rebuilt Allison automatic is a bargain.
Fourth, don't worry about the tires. By the time you have the bus converted you will most likely need to replace the tires due to age. So why spend more up front for something that will need to be replaced at a later date any way?
Good luck and happy trails.
Mark O.
Winlock, WA
boy does she know me. we would like the freedom to do it our way and not go broke trying to it, not sure i think iam partial to front engine ,because like some one posted i want to build a small porch . also for the motor gurus are these 5.9 the same ones as in the dodge pickups? if so has anyone ran into the kdp ( killer dowel pin problem)? i wll find the article so everyone does not think i am nuts.