I have had excellent results with the Lithium Batteries offered by Antigravity on several bikes. No more Battery Tenders, (which still kill batteries in my experience if you don't watch them and maintain a fluid level on long term charging) acid stains, or refilling batteries. The battery can sit for a year and still be near 100%. I have them in Kaw Triples, Yamaha RZ and RDs, a Norton Commando, and KTM dirt bikes. Some of these bikes sit for long periods and always fire right up.
What will kill them is parasitic drain, and overcharging regulators, which don't do much for Lead Acid either. There are several manufacturers of Lithium batteries on the market but I started using Antigravity mainly because of a thread on ADVRider. A guy there who is in the UPS Power Supply Business tested the Lithium brands and gave Antigravity the best grade. The Lithium batteries are more money but if you are replacing batteries a lot they are a good investment. I like Lithium just for the install and forget it factor.