Depends on your uses. For tri related activities and racing - 935.
But if you want to wear it as a daily watch or do other outdoor activities such as hiking, climbing, skiing etc. that you want mapping or activity tracking the Felix line is the way to go. Quick change watch bands, sapphire glass, and if wanted music on the plus line makes it is one quiver watch for you.
Or if you are a diver - step up another level to the descent mk1 which is a Felix 5X with full dive planning and computer built in. I have this and used it on a multi day dive trip a couple months ago. My guides were impressed with it particularly the compass functionality for underwater navigation.
This all the way, daily wear the Fenix is the way to go, especially with the sapphire glass. I'd also spring for it new vs refurb, I have not had good luck with the refurb watches.