About two years ago I was having starting troubles even though I had a relatively new battery that tested great at Auto Zone.  After reading up on bus batteries, I decided to take ratwell's advice and get an Optima Red Top.  I was an amazon prime member and it is a sealed battery so I was able to get it without tax or shipping for about $140.  That solved my cold weather starting issue and I have not worried about it since.   

A few months ago I went out and Sweetpea was dead.  Really dead.  I took the battery to AZ and they said they wouldn't test it unless it was charged (their new policy).  They used to charge them, but whatever.  So I took it home and tried to charge it.  My charger would not indicate that it was charged even after a long time.  When I put it back in the bus, it still wasn't charged enough to start but it had enough power to reveal to me the cause of the dead battery.  I could hear a muted whirling of an electric motor (not the fuel pump).  Come to find out that one of my boys must have found the sink kill switch and turned it back on.  So they had turned the sink pump on and left it which drained my battery completely.

Sad about loosing a $140 battery just a few years in, I went and dug out the paperwork that came with it.  There I found instructions for re-charging a deeply discharged battery using two batteries.  All this to say that it worked and I was able to bring back the Red Top and haven't even had the slightest problem with it since. 

Last time I was in the store, every battery was pushing $100-130 and the Red Top was $200.  I just checked with Amazon and you can still get one for $140 if you have Prime.  I've never seen a standard battery recover so well from a deep electric motor caused drain (it had been on for at least a week).

My point in all this?
Dig the red top.