So, a few months back I switched to the ShotScope system (H4). I really like it and am going to stick with it over Arccos. First, if you get just he gps unit w/tracker, it is the same cost as just the annual subscription for Arccos, but of course it is a one time purchase, not a subscription based thing. Here are my takeaways:
Sensors: Definitely prefer the ShotScope. They are black and blend more with most grips (not green/black), they are much lower profile (I often found myself grabbing my arccos sensors when I had them on, had to remember to grip lower on the actual grip), and they don't die. I really like the last part, as I have had to go and buy replacement sensors from arccos when the clubs I use most at the range died quicker than the others, and then wouldn't record shots on the course.
Tracking: Still prefer the ShotScope. At least now, when it doesn't record a shot, it is because I was dumb and forgot to tap it to the gps unit, not because it didn't do what it was supposed to. Even with my phone in my pocket (I had the Gen1 link and gave up on it quickly, complete garbage, missed at least half the shots and spent waaaaaaay too much time during the round adding them back in), it still occasionally misses shots (more time editing during the round) and was horrible at putts (always told me I 3 putted, no matter how many putts i took. Unless I actually 3 putted, then it said i only took 1 putt, again more time editing/fixing during the round). ShotScope also vibrates when you tap it, so you know that it has recorded, and you can also take a quick peek at the screen to verify.
GPS: This is pretty even. With arccos it uses the app, so it is on your device and obviously that is a much larger screen than the shotscope. But the shot scope gives you exactly what you need when taking the shot, without all the other stuff. With Arcoss to view you have to take your phone out of your pocket (unless you have link and have your phone readily available in/on your cart). Shotscope, the little gps handheld is tiny and is held to a clip by magnet, so just pull it off your belt, look, then place it back. The only issue i have had with shotscope is that it can sometimes take a while to acquire the GPS signal....i have remedied this by simply turning it on as soon as I get to the course, but if you forget it can be a tad frustrating.
App/Editing: I think this one is kinda a draw as well. Arcoss is nice in that you have it going on your phone and can edit in round (but this can be bad as it can slow you down, or be more of a distraction instead of focusing on your next shot). The ability to edit in Arcoss is also easier than in ShotScopes App, which can at times be a little frustrating to deal with, until you are more acquainted with it. Also, you can not edit during the round, you have to wait until after. This is kinda good and kinda bad as you don't waste time during the round fiddling with it, but you do have to remember what club you used, how far out you were, and roughly where you were for the shot you are editing. Both give you TONs of stats about your rounds, average club distance, etc. Also, Arccos will act as a caddy for you, based on your stats, common misses, etc. and recommend a club for each shot. Shotscope does not do this.
In the end, both provide very similar data, but with not having to rebuy sensors when they die, no subscription fees (arcoss was $90, then it was $120, now it is $155....how long till it's over $200??? This is what actually got me looking for other options) and missed shots that are my fault (as opposed to the technology missing the shot), ShotScope is definitely my choice. The H4 is a one time cost of around $150, that's it, no additional subscriptions, no having to rebuy sensors, etc.