Both players (Along with Peacock) are head and shoulders above almost everything we have at International level Currently.
Unfortunately the Standards in SL mean are so low that we have to watch the current crop parading around such as JJB/Wilkin/Sinfield/Westwood/Langley/Purdham etc at international level and yet were told that standards are rising year on year!
As both players played the majority of their careers at 2nd row/Loose I would be inclined to judge them on those positions.
Me personally I would have both in the team but if I had to pick one I would (Obviosuly/Biased whatever you what to Think) pick Farrell.
Teams need different types of players to make a Great Team, IMHO in Sculthorpe & Farrell you had the perfect compliment.
Both got great Hands, good kicking games, ability to make a break, run the ball in tough when it was needed.
Farrell Better defensively, Sculthorpe better attacking player.
2001 1st Test v Aus (I think 2001) sums it up for me.
Sculthorpe scores 2 x tries (And a Drop I think) and caused Aussies all kind of probs playing at 6
Farrell kicked 3 or 4 goals made about 40+ tackles and came off covered in Mud & sweat.
That was a perfect combination and one I can't see being repeated at 6 & 13 for many years ahead!