What makes a great song in your opinion?
Great melody, catchy hook, intelligent lyrics. Good guitar playing doesn't hurt, but not completely necessary to make a great song.
A great songwriter...
"...I’ll wake up some days, and I never really have a problem sitting down with a guitar, there’s always something, you know? I mean, I can do it now. It may not be good, but I can get something together. I love the fact I can do that. They talk about a gift and all that, but the more I go on I realise that it is, like, a gift. We used to say like, you know, ‘he’s got the gift of the gab’ or ‘he’s got the gift of music’ and when you think of it as a gift, it really is very special. So I feel very privileged because not everyone out in that square and can do that, in fact, there's probably hardly any of them walking around there can do it."
--Paul McCartney, 2012
If it has the word "freaky" in the title.
A great song either makes me think or makes me feel. That's about as simply as I can put it.
If you like it and want to hear it again then it is a great song.
No need to be well written, or a serious piece of music ........if it moves you somehow it is great.
Secretary of Crackwood Addiction
This may be a sub-section, but the solo in a good song should follow and expand upon the melody rather than just a bunch of notes in the correct key and over the matching chords.
2013 LP R9 VOS, SG Standard VOS
2012 P22, IRW
2014 Clapton Strat
Suhr PT 100 Amp, Forte 212 Cab, Marshall 425A Cab
Marshall Vintage Modern and SL5, Fishman Loudbox