I like all three of them for very different reasons, and every time I start to choose one over the other, I remember other favorite scenes from the others and can't make a decision again. I love the silliness of L&C acting like children and Clark burning the heel off Lois's boot in SG, but I also love the whole "look who's coming to dinner" insanity from HIWTHI, as well as all the funny lines from Mxymas. I love the romance of the end of SG and the end of HIWTHI, as well as the moment when Lois breaks out of Mxy's spell in Mxymas. I love the drama and angst of Clark's 'deathbed' scene in HIWTHI, but I also love how much he has grown by Mxymas and his determination not to be blackmailed into leaving Earth so Mxy won't hurt them more.
Three good eps.
