It comes down to two batteries for me:
1- Any AGM, no spills and long shelf life. Higher initial cost, but if taken care of long life should be expected.
2- Any cheap conventional. Most manufacturing tech. has plateaued on conventional batteries. I bought the cheapest one I could find at this website:
http://www.batteryxpress.com/store/scripts/prodView.asp?idproduct=96It came without acid (saves on shipping cost) and $2 for acid at the local interstate battery got me going for the cheapest way possible. With careful care even a conventional battery can last 5 years, but that means proper floating, proper temp. for storage, and most importantly checking each cell's SG regularly and keeping it full.
Prices on AGM have gotten better, if you can afford it I'd go that route. But if you're like me and ride on a budget, I highly recommend the website above; it took me 2 or 3 days of calling shops and scouring the internet to find the best price on a stock battery for our bike. Hopefully my time spent can help you as well, that's what the forum is here for.