I tend to buy a name brand battery....like Yuasa.  I stay away from most things made by BikeMaster.....they tend to be poorer quality.  My friend who has been working on bikes for more than 40 years recommends batteries made in Japan, Taiwan or the USA...Chinese made batteries tend not to be as reliable or durable.

I only buy the AGM batteries, as they can't spill and don't have a vent tube that tends to rust parts when it vents.

The only downside that I know of from the AGM batteries...is they tend to give almost no warning when they decide they have had enough.  The factory Yuasa AGM battery on my Honda worked for 11 years straight without a hiccup.  One afternoon I started it up and rode to the hardware store, then started it up and rode a mile down the street to the gas station.....and the battery wouldn't even turn the neutral light on when I finished getting fuel.  I got a jump from a car and rode around for 30 minutes to see if the battery would charge, and when I got home it once again had no battery power.  I tried charging it and could get nothing.  The battery went from working to dead in a period of 1 mile!    

I got a Uasa for the Kawasaki, parked the bike, health reasons, and the four wheeler battery puked.. so, I stuffed some foam rubber around the smaller battery for the 650 than the battery for the 250,, confusing, innit?, and it's been good for four years. I rarely run it, why the battery has survived beats me. I LIKE the mat/gel batteries, I'm not sure they're really that much better, but checking water on the stock savage means pulling it. Given the option, I'd go gel, but, if money was tight, UASA,

+1 on the AGM. got one at adv auto parts at a big discount with online coupon. first one was crap out of the box. second one i made them test in the store and it's been running for 2+ years with no issies. i put it on the trickle now and then for a few mins just to make sure it's topped off and it rarely needs more than 15 mins on the trickle before it tells me it is full, and i remove it promptly to avoid overcharging.

So far so good with the Duralast Gold AGM.  It's always full, has never needed even one minute on the trickle charger.  I ride every day though no matter the weather.  No fuss battery.

Dangitt, Dave, now I gotta go add another line to the scoreboard..
We've got
Solved someone's problem, and Dave has two stars, I think Rowboat has a question mark, and I have a red face with a big frown and a tongue sticking out.
Now we need a way to keep up with referenced sites that help..
This looks good, and Dave gets the first star, Uhhgain,