My best kit is always the one I'm working on. Constant improvement and applying new techniques is always a goal for me.
So far, I think my favorite has been Tamita's 1/35 Panzer II desert tank. It was small and simple, and was really my first attempt at painting camoflague and applying washes, and just turned out to be a neat little build.
I think the worst is the 1/48th AMT/Ertl A-10 Warthog I am currently working on. The details are poor, fit is worse, and there are warped pieces, flash, and ejector pin marks everywhere. I swear I have the last boxing before they threw the molds away! But despite the frustration, I'm still committed to making a respectable model out of it. Will just take a little time....and putty...and sanding.......