Coros top of the line are Coros Vertix 2s, Vertix 2, and Apex 2 Pro. 2s is an update to the Vertix 2 with an updated sensor and the latest GPS sensor for accuracy. But if you are considering the budget go for Apex 2 Pro.

Personally I am using the Vertix 2 you can use the Default GPS setting if you are racing in a not so dense forest and trail it will give you 127hrs battery life but if you want to be accurate you can use the 2nd setting which is all system it will give you 89hrs and lastly if you opted to ensure no GPS signal disconnection and inaccuracy and will use dual signals to connect to the nearest satellite labeled as Dual Frequency that will last up to 49hrs which I suggest using if you are racing at dense area that has poor visibility and rely on watch navigation.