To be completely honest. Sphax PureBDCraft is superior in all fashions.
http://bdcraft.net/download-bdcraft-texturepacks
It's available in 16x16, 32x32, 64x64, 128x128, 256x256 & 512x512. I recommend using the 128x128 version. Anything below that looks pretty bad IMO and anything above that will require you to have pretty good hardware because it will use up a lot of RAM etc.
I use Sphax PureBDCraft 256x256. I have a GTX660, 16GB RAM and a Quad-Core processor.