I think, for classical guitar, and classical music in general, MuseScore is absolutely amazing. It's totally free and very nice for classical guitar music. It offers absolute freedom of creation, musically and graphically as well. It handles four totally different voices, each with multiple-note possibility, so you can solve all your voicing problems. Fingerings (right-left) plus all the usual classical guitar markings can be neatly added wherever you like! It needs some learning, but it's worth - the result is really beautiful, absolutely print quality. You can be (and need to be) a real graphic designer with this. Plus you can download really nice (and big) sound fonts to play, enjoy and assess your music. It exports, imports MIDI, exports PDF, incorporates pictures or anything (text, PDF) into your printed score and has lots of nice functions, synthesizer, mixer, etc. It has internal fonts for text, too.
As I have experienced, GP5 &GP6 is, rather for those who like pre-set, fast results, don't want to fuss about minor details and need TAB most of all. My pop musician friends usually prefer those editors.
There's a lute TAB editor around as well, which is an older, and not-so-worked-out program, so some experience is needed to compile it and make it work, but is well worth the effort - the result is absolutely smooth, special and true to historical sources. If anyone is interested I can dig out the address. You can find it if you type 'lute TAB' in a search engine.
TablEdit is better than GP6, although simpler, but this is rather an advantage. It has a huge and useful flamenco library, too.