I have a basic knowledge but I want to learn more. Im looking to get one but not sure which one. Any help is appreciated.

consider videos too
lick lbraey harmony and theory taught ms well
there's some pro ably better ones though
On playing the Paul Gilbert signature at the guitar store extensively, my missus sighed:
"Put it down now, It's like you love that guitar more than me!"
In Which I replied.
"Well it has got two F-Holes!"
Not sure how 'basic' your knowledge is but the "Idiots Guide to Music Theory" served me well. It's the only theory book I have so I can't compare it to others but when I was getting lost looking at things on the net this book helped me find my way again.