I haven't looked much at these as I'm still using a really old CTEK charger that is branded as "Porsche" - it's technically not even the right one for an AGM battery (even tho my 911 does have an AGM), but it has worked fine for many years. The downside to this specific charger is it only has a cigarette lighter plug, so it doesn't work on the GV80 (I tried, the cigarette ports on the GV80 don't allow trickle charging).
If I were buying one today, I think this is what I'd get:
The award-winning CTEK MXS 5.0, offers a unique eight-step approach to battery care. Read more at ctek.com
smartercharger.ca
I also plan to try my off-brand battery tender that I purchased from Amazon to see if it works well with the GV80. There are quite a few time periods in the summer where the GV80 sits for 1-2+ weeks at a time as it's mostly only used as a highway/spare vehicle in the summer months.