Kendrick is more like a passionate poet/conceptualist when it comes to how he approaches rapping, which is fine, but there's a reason why people draw those Pac comparisons, and it isn't just because they're both from California.
Cole is more in that Jay-Z/BIG lane where he is a lyricist. Rhyme schemes, entendres, flow, etc.
There's nothing wrong with preferring the passionate poet style more than the technical lyricist style, but for me and my taste, the technical lyricist is always going to be more impressive to my ears because I interpret them as being the best of the best at what a rapper is supposed to be.
I'm fascinated and captivated by geniuses of a craft who are the best at what they do, whether it be athletics, entertainment, or art. Not the most popular, or who gets the most bytches, or who has the best machine behind them. Who is actually the nicest when it comes to SKILL? I feel it is MUCH easier for a technical lyricist to slide into that poetry style than for a poet to give you a scalp-scorching 16.
That's why Lupe is the GOAT to me, and why I admire rappers like Nas, Andre 3000, Jay, Eminem, and BIG more than anything else. They're the best at the actual job description - creatively and technically rhyming words together.
PS: For all transparency, Kendrick is in my top 5 and Cole is not. TPAB is arguably my 2nd favorite album ever, and clearly Kendrick has the better discography. But when it comes to ACTUAL RAPPING? Cole is better at this point in time. Where Cole has evolved as a lyricist, Kendrick has arguably regressed(Love MMATBS, but the bars aren't sharp like that).