Yes guitar cables indeed make a significant difference to tone via capacitance and their effect on passive pickup resonant frequency with the associated hi end roll off just above that frequency, to noise via shielding type and ability to reject interference and triboelectric microphonic noise (handling), gig success via construction (including cable shield type due to tensile properties) using variable quality connectors with variable soldering quality and variable strain relief effectiveness regarding the chance of failure and affecting longevity.
These things and many more are described on many pages from here:
http://www.shootoutguitarcables.com/guitar-cables-explained/introduction.html
The guitar cable is a seemingly simple product that serves a very important function and is asked to do a great deal under less than ideal real world conditions. However very expensive cables typically go into highly esoteric realms borrowed from the hi-fi world and at that point cable makers and retailers are typically unable to provide sound empirical science based evidence and/or reasoning to support marketing claims.
'I would always naïvely get the cheapest cables. Now, I'm understanding the differences more.'
Good to see that you have seen the light! Look to science and engineering, avoid snake oil and you'll be OK!
Hope this helps.
Cheers,
Marc, Director
Shootout Guitar Cables, UK