I use Tractive, and it works well for our needs. I have the classic which is GPS only, though I see now that their new model does include an activity tracker - I can't comment on how that works, though, since mine doesn't include those features.
Garmin does not appear to have a combo GPS and health tracking unit - it's either GPS only or a health tracker + 'trainer' with no GPS function. Just an FYI, the 'trainer' function is a shock collar, which is a tool that doesn't work for all dogs and can actually cause worse problems in some. I and many others do not condone the use of shock collars by most people in most cases, so unless you are a very experienced trainer with an understanding of how shock collars function and what the risks are of using them, I'd avoid that.
Many dog GPS collars (whether they're also health trackers or not) require a subscription to gain access to the company's satellite services and function. Garmin does not if I remember correctly from my own research, but comes with a hefty price tag for that privilege. Another consideration is your dog's size - some of the options are just too bulky to work well with a small dog, especially if you're using them in areas with a lot of brush the collar could get caught on, as I am. Lastly, if you plan on traveling abroad with your dog (well, not right now, obviously, but in the future, haha!), make sure you get one that will work outside the US. The Whistle has phenomenal reviews and I'd love to try it, but it's US only right now.