Which are the "best" Intel AHCI/RAID drivers?

Yes!

The latest and probably best Intel EFI “RaidDriver” from the Intel RST v14.8 series is v14.8.2.2397.
So if you want the best results while using the Intel RST(e) RAID drivers of the v14.8 series, I recommend to update the Intel EFI “RaidDriver” to v14.8.2.2397 and to install the Intel RST(e) driver v14.8.12.1059 WHQL.