The small Battery Tender jr, is just a maintainer,which is fine if your voltage doesn't drop too low,say below 12.2 ish. The Optimate 3 is an actual charger,the are many different Optimate charger now, but at a minimum the 3 is great. Yuasa has a couple,they have a new 3 amp charger,desulphate mode one. Ctek is another good one,been using one of those the last couple years. Optimate is the brand dealers HAVE to use here (Honda and Kawasaki for sure,can't remember what Suzuki and Yamaha insist on) to claim warranty ALL stock batteries.I have recovered a few customer batteries and one of my own but usually you just get 3-6 more months out of it.
I have also had a couple die(1 Batt Tender,1 Yuasa) but they were both past warranty .