Just battery life and battery reliability.
I have had as many battery issues with my 2 Terics as probably anybody on this board. Between the 2, I've had something like 8 or 9 battery replacements now.
Even when they are at their WORST, my Terics have always had plenty of battery life to last for nearly a week of diving every day.
And, I have never had an issue with reliability in the sense of a battery dying and causing me to miss a dive.
The ONLY issue I have had - and I think this is consistent across all the Teric users that have had battery issues - is that they discharge more quickly WHEN STORED than they are SUPPOSED to. I.e. the manual says that if you have charged it and then store it, you should top up the charge every 6 months. Well, at the worst of mine, I've needed to top them up every 1 month.
And even at their worst, the self-discharge has minimal effect on how it performs when you are using it every day. On a 1 week liveaboard, when the battery is new and good, maybe it will go all week without HAVING to be charged. And when the battery is at its worst, I've had to charge it once during the week.
So, yeah, the Garmin battery will go longer on a full charge when you're wearing it as a daily wear watch. Maybe it will even do more hours in the water. And yes, you seem to be a LOT less likely to need a warranty battery replacement on a Garmin.
But, to ME, the issues with the Teric battery are annoying and yet so minor that the battery would not be high on my list of deciding factors between the Teric and the Garmin.
I do understand that that is just me. I dive all the time and I don't wear a watch of any kind when I'm not diving. So, keeping my Terics charged is not an issue. I don't need to remember to top them up every month or two, as I'm using them way more often than that. And I don't care about "sports watch" functionality. Obviously, YMMV.