I've got two Tracker Marine Lithium 12v batteries wired in series for my trolling motor. Works well so far.
I heard good things about MillerTech batteries and now have one for my main boat battery. Only issue I had with it was self induced. I left the master power switch on and completely drained the battery (it was new). The charger would not charge it at all at that point. Call Millertech and they said to jump it with a lead-acid battery I still had on hand. That worked to "wake" the battery up. However, my NOCO charger still would only bring it to 50% charge. I ended up having to get one of Millertechs own brand chargers to get it back up to 100%. Works fine now.