Hi, Greg,
IMHO, the Academy kit is nice, worth building if you can get it cheap, but not quite as good as Hasegawa's. The Hasegawa really represents the F-15D. To make it a "proper" E , with the wider wheels and tires, more bulged gear doors and miscellaneous lumps and bumps, you can use the Paragon resin conversion set, which is out of production, hard to find, and somewhat expensive. Of course you can always just build the Hasegawa kit unmodified, paint it Gunship Gray and you will have a beautiful model which very few people would realize wasn't "quite right".
However, since you said you want the best, I'd have to recommend the Monogram Pro-Modeler kit, also released in the U.S. in a Revell box without ordnance, and by Revell of Germany with Tiger Meet decals. It is easily one of the best 1/48th scale jet kits ever...beautifully molded, well engineered, accurate, and great value-for-money. The masters were done by Bill Koster, who is doing the masters for the upcoming Revell/Monogram F-18E Super Hornet. (Can't wait for that one to be released!)
Hunt down the Pro-Modeler kit. I assure you, you won't be disappointed.
Best regards,
Jim Whitley