There are tons of amps capable of getting great clean sounds. Depends on what flavor you like best and how much overhead you need. AC30's are great for chime, sparkle and jangle. Fenders offer gorgeous cleans all over the board from grindy tweeds to loud clear twins. Then there are older marshalls - a plexi isn't exactly "clean" but with single coils and the guitar's volume rolled back a bit you can get some incredible thick cleanish (think Jimi) tones. Even Boogies can offer decent cleans - my Mark IV gets a nice bouncy shimmery clean sound with the right guitar.
Then there's the whole panoply of boutique gear, most of which are interpretations of classic (marshall/fender/vox) circuits with new features.
If I could find one "best" clean amp I'd sure free up a lot of space in my room is all I'm saying!
