Monte, how do the Pro-twist handles compare to the Ergo-twist?
The main difference is the square part in the middle of the handle of the Ergotwist screwdriver vs. the round handle of the Protwist screwdriver. I like the color coded newer Facom screwdrivers, but i also like the older "French design" screwdrivers and i guess you`ll have a better torque transfer from the hand to the handle because of the square handle. But i think it is rather a matter of taste which you`ll like better. Actually I`m on the lookout for more of the older generation drivers.
Which driver do you favor most

?
This is a good but difficult question which i unfortunately can`t answer. They are all somehow more or less ergonomic, some people prefer plastic handles some rubber etc. i personally prefer "rubber" coated screwdrivers were the complete handle or at least 50% is covered with rubber and ideally the "twisting zone" too. While the "twisting zone" should be round the rest of the handle should have a irregular shape (hexagonal, trigonal etc.). I also like the heavier feel of "go thru" screwdrivers so maybe i would vote for the Felo "550 series" or the "Witte Protop 2 Impact" or similar.
But it`s always a matter of how you hold the screwdriver too. Some drivers have bigger handles than others with the same tip size, i prefer smaller sizes for handles, the majority seem to prefer bigger handles, and also new styles appear every year like the new Hazet "Hexanamic" which ain`t bad (i also like the older style very much), the PB swiss ones are nice, the Wiha Proturn, the.......

The best is to buy them all
Some speciality "screwdrivers"