Everything being equal, the choice is a lot simpler but not everything is equal.
I've been using a Garmin Vivoactive HR+ for almost a year now. Picked it up to replace the Microsoft Band which was tragically killed off by Microsoft.
The Vivoactive HR+ has served me well and I really like the water resistance. The software on the other hand is a nightmare for a Windows Phone user.
I do not get push notifications, synchronization is a crap shoot and there are times the Connect Mobile app completely fails to work.
The Vivoactive 3 come incredibly close to what we had with the Microsoft Band and just looks great.
However, Fitbit's Ionic also comes incredibly close to what we had with the Band and also looks good.
Fitbit's software is far more successful than Garmin's on Windows 10 (Mobile and PC), though.
I don't care much about the onboard music storage and having onboard GPS and water resistance is a plus.
I do have a Garmin scale which would need to be replaced.
There is the option of switching to an iPhone, where the software issues are not as prominent, and stick with Garmin but that's an awfully expensive solution.
I guess what I'm asking the group is are there any overwhelming reasons not to switch to the Ionic? Is there hope that Garmin will get off their butts and give Connect Mobile some much-needed attention?