Of the general stroke play courses, Bethpage is definitely my least favorite. The greens are generally boring (with the obvious exception of 15), the fairways are all the same width, and the changes in elevation are either easy to work around or impossible to do so.
Merion is actually one of my favorite courses (particularly the back nine), but that might just be because I seem to have a knack for playing that course over others. Olympic makes me want to rip my hair out, but I think the challenges it provides are at least varied and interesting (although the next time I hit a tree on a tee shot I might cut somebody). Congressional was where I shot my first -10 or better, so I have a soft spot for it. The links courses are fun, usually. Kiawah is, well, enh. I like Oakmont a lot even though I hate holes 1 and 9 with the fire of a thousand suns (the rest of the course I find quite fun).
I will note that I really dislike Whistler a fair amount as well. The way that the greens are mapped frustrates me to no end.