
I mean, I'm not gonna but them in the top 5... but I'd easily put them over a good third of the canon, including about half the Heisei films, a good third of Showa, and Shin Godzilla, for enjoyable/interesting characters.
Then again, I think a lot depends on the definition of 'worst' or 'good' being used here. For me, the Megalon cast, being ciphers, are unwatchable, dull, and frustratingly... well, ciper-ish. Whereas the cast of Final Wars are over-the-top (and the dubbed versions are a bit too whiny), but they're entertaining to watch. So I'm defining 'good' as 'entertaining' and 'worst' as 'dullest/least engaging,' rather than any literary standard or standard of development-level.