What do you mean by "best"? They all do pretty much the same thing, cutting the fuel and/or ignition for a predetermined time, thereby unloading the gearbox. Most of them are tunable for how long you'd like that cut to be.
I had a Starlane Da Vinci dash on a previous Yoshi'd GSXR race bike, it came with the shift sensor so I used that rather than the Yoshi EMPRO, cutting ignition
Nemesis Q/S on a current 749R race bike, cutting fuel
Dynojet PClll Q/S on a current 851/926 race bike, cutting fuel
One thing worth noting, the ignition (rather than fuel) cut results in decent "POP!" during changes, so can be an issue for noise testing if you head to the track.
To be honest the PClll pull sensor setup on the 926, with a default 60ms cut time feels smoother than the 50ms cut time on the 749R, so I'll be changing the Nemesis cut time when I get around to it. (but could be gearbox, or simply the extra hp/revs from the 749R) I had to download some software and enable the Q/S function on the PClll but your PCV is already enabled so it is literally plug and play. Note, there is a minimum RPM activation (4000rpm?) so you don't kill the engine if you bump the lever while trundling around a carpark or such like.
Spending more money won't buy you a better Q/S, you'll just be adding more complexity and doubling up on functionality you have already paid for, so just go with a Dynojet unit.
To rub salt into your wound, I just this week bought exactly what you want off Evilbay, 848 shift rod and pull sensor to adapt to my old '06 R1 road bike. Cost me $99US