XMRig nVidia vs XMR-Stak... Who's the best?
XMR-Stak start from 0 Hashes
Hashes sent to pool in 30h: 298,753,696 + 2 % dev fee
Hashrate: 2822 H/s

XMRig nVidia start from 0 Hashes
Hashes sent to pool in 30h: 303,238,595 + 1 % dev fee
Hashrate: 2836 H/s

At total hashes I added the fee, to end up with the real hashrate of the miner, from pools point of view.
In miner's console the hashrates are bigger, around 2850 H/s for XMRig and 2848 H/s for XMR Stak, but of course they varry a bit durring the day. The difference between pool and miner reported hashrates, assuming pool dosen't cheat, may come from the time lost when receiving and starting the work to a new block, and from switching to dev pool and back, besides the 1-2% time spent there.