Vivosmart HR+ for me, was £100 from Amazon. Vivoactive looks nice but I wanted something I can wear as an all day activity tracker, and the Vivoactive is twice the size.
GPS accuracy is a lot better than my phone’s, and from reviews the heart rate tracking is about as good as you’ll get without a chest strap. It’s also fully waterproof if you’re ever inclined to take it swimming.
Only downside for me is no cycling specific mode, it will still track GPS route and speed and I can set the activity as cycling afterwards so it’s not a big deal.