For XVG I was on zpool for 12 hours with zero rejected shares, but they take too much and my wallet for whatever reason is set to mine all blake2s instead of just verge then autoexchange. Unimining = 10%+ rejected shares. Antminepool I've only had one rejected share so far, but hasn't been running long. Going to run for 12 hours and see the difference in currency between the two.
I have observed the same. I am more 15+ hrs with 18.5 GH/s on zpool and only got 40% of what whattomine is reporting for the hashrate. I am not sure about accuracy of whattomine on xvg-blake2s either but judging by other coins they have listed with reasonable estimate accuracy I would be suspicious on zpool.
Looking at other's response it seems,
zpool - less connectivity issues but lower payout.
Unimining - connectivity issues mainly cause of surge in mining.
Antminepool - less connectivity issue. payout is slow because it's much smaller mining pool.