There’s not a lot different between Polar’s H9 and H10. In this article I explain what actually is.
What are the differences in between the Ignite and Ignite 2? Is the Ignite 2 worth your money?
What are the differences in between the M and M2? Is the M2 worth your money?
Finally you can use running power in a workout.
An iteration of the OH1, Polar addressed some usability issues and increased the range.
First off, the Ambit 3 is available in Peak and Sport edition, I’ll use the Sport edition for this comparison as I feel it’s the better option for a triathlete. The Peak is the better watch, but if you swim, bike and run (or any of those by itself), the Sport edition is all you need.