I was wondering about this over the weekend: how much is down to liking the song, how much the sound of the guitar and how much the actual "tune" of the solo? There are songs I really like (and bands/guitarists playing said song) but the solo in the song sucks golf-balls through a 50' hose (Alex Lifeson springs to mind - I'm a big Rush fan, but think pretty much all of his solos are awful); there are bands whose guitar sounds like it's being played on a sub-£50 Argos* guitar+amp bundle, which totally spoil what might otherwise be a good solo; and there are solos which aren't necessarily "amazing", but the guitar sound is gorgeous so the solo is lovely to listen to.
* Apologies to those not in the UK for the cultural reference.