Shot Scope. Main reason is there is no subscription fee. I just bought the X5 watch, tagging is far better than previous generations but it still has some flaws. Some features of the watch are buried in the UI, which can be frustrating since you don't want to be messing with the watch while playing. The developers do listen to the community and continually push updates to fix bugs. Overall, I'm happy with shot scope but I've never used Arccos for comparison.