I don't know why El Al selected the RR engine. But the 77W programme was already in an advanced stage and Boeing's exclusivity decision in favor of GE had already been taken when El Al ordered its first 777s.

http://www.boeing.com/news/releases/...e_991027b.html

http://www.geae.com/aboutgeae/pressc..._19990707.html

The decision was surely more "emotional" than practical. El Al very much wanted to buy Airbus planes but strong (and justified) US pressure forced the than State-owned airline to select Boeing. The same scenario happened two years earlier when El Al wanted to buy the A320 family of aircraft instead of the NG737s. I guess El Al's management felt so frustrated to be unable to "independently" select its fleet that it decided out of rage to select at least the European engine...

Now, if someone has a technical point clearly in favor of the RR option, I would be very interested to read it........