Best 1:144 Saturn V - Airfix v Monogram??

Tony, I don't want to disappoint you, but I must say neither one. This may give you some clues about both kits : http://www.apollosaturn.com/frame-mod.htm
Enjoy !

Both kits have their strengths and weaknesses, and there is plenty of reference material online for building an accurate Saturn V. The Airfix kit probably offers the best starting point for an "enhanced" version. But that's just my opinion, and there are folks out there who know far more than I do about modeling the rocket.