Fenix 6 here. I probably only use 2% of the features, but its been great. Also being in the ‘Premium’ end of the range they’re not as buggy, which I’ve found with the forerunner 2 ranges. I record 6 or so 30 minute activies and one 4 hour activity over the course of a week on a single charge possibly?
They are quite big, but you get used to it, it depends how thick your wrist is. Some shirts need the cuffs unbuttoning to get them over the watch.
Maps are handy, but the UI is so fiddly its quite difficult to use, and you may forget which combination of buttons to press.
Definitely worth getting second hand as they are pretty indesturctible, probably more so than a Casio G Shock.