Tidier, the tidiest

Jollier, jolliest

funnier, funniest

noisier, noisiest

more boring, the most boring

more expensive, the most expensive

more exciting, the most exciting

higher, highest

wiser, wisest

nicer, nicest

ruder, rudest

cleverer/more clever, cleverest/the most clever (и так, и так правильно)

more dangerous, the most dangerous

more narrow, the most narrow