I think Weird Science would be my favorite of the John Hughes-directed films of the 1980's. Although Planes, Trains and Automobiles and Uncle Buck are quite spectacular as well. I wouldn't say Weird Science was the "best" of the bunch, but it's still my favorite. I've found that a lot of the movies that I ended up revisiting the most feature a couple of nerdy/misfit/outcast friends/brothers in some kind of wacky misadventures. Put Strange Brew, Wayne's World or Bill and Ted, Lebowski (it counts) on in front of me and I will stop anything I'm doing and stay put until the credits roll. (Once I can own it and watch it on a regular basis, the critically maligned Pineapple Express will be added to that list as well.)
In addition to Weird Science being loaded with nerdiriffic shenaningans, there is also some great and hilarious dialog between Garry, Wyatt and their digitally-created Frankenbroad Lisa. I've also always felt there were some great casting choices in Weird Science; Anthony Michael Hall, Robert Downey Jr., Bill Paxton, Michael Berryman and that chick from Night of the Creeps, Return of the Living Dead II and Killer Klowns From Outer Space - that's good casting if I ever saw it.
Anyway, I've said enough for one post, but while I'm talking Hughes, I just need to state, for the record, that it is my opinion that The Breakfast Club has by far the worst out-of-nowhere dance scene in the history of time and space. I cringed so hard the first time I saw that scene that my face has still not fully recovered. It's caused some problems for me over the years. Oh, and Ally Sheedy was much hotter before they Ringwalded her up at the end. Thank you for listening, I had to get that off my chest.
You're stewed, buttwad!