All batteries will eventually fail. As long as you keep the electrolyte topped up with distilled water, the terminals and case are clean, and your charging system is working correctly, you should get 2 - 4 years of service from your average Lead Acid battery.
An AGM is maintenance free, vibration resistant, and arguably more reliable, but is it worth the additional expense? Only you can answer that. Our charging systems are not refined enough to deal with Lithium batteries, so they aren't an option in my opinion.
I only put my battery on a tender during the winter, when it is being stored inside. Even then, I only have to "top up" the battery once or twice in the 3 - 4 months it is being stored. When the ignition key is turned off, there is nothing drawing on the battery. No clock, computer, alarm system, etc, so leaving the bike for a week or 3 shouldn't be a problem.