And PLEASE !!! FIX your PING!!! 260ms is NOT GOOD FOR MINING!!! You must have below 100ms, 30-60ms will be awsome.
I'm in Australia and I average around 250ms ping which seems to be totally fine. My rejected share ratio averages around 0.5% I agree lower latency the better but I can say with confidence that anything around 250ms is fine.
IMO. Miner stability over pool ping times. Running 4x 1080tis at the same time, the rejection rate does not seem to depend on ping.
For example, when I mined ZEC, I was getting ~ 10ms ping to pool, but accepted shares >100ms (per GPU).
Many of my shares were still rejected. < 1%
Stale shares, GPUs making errors (bad drivers?).
Depends on how much hashpower you have at your disposal.