Deltran Battery Tender Plus.
http://www.amazon.com/Deltran-Battery-Tender-021-0128-Charger/dp/B00068XCQU
3 1/2 years of continuous use for me.
6 1/2 years left on the 10 year warranty.
2,820 customer reviews on Amazon. 86% 5 star, 9% 4 star.
If all you want is a tender, the cheaper battery Tender Jr (.75A) is fine, but 5 year warranty instead of 10 year. I got the Plus (1.25A) because I wanted a bit more power for an Odyssey AGM battery in my truck that runs an ARB Fridge Freezer and therefore gets run down more from that extra load.
Neither are good for recharging dead batteries, but both are good maintainers.