We don't know the contributions of each member. Like you said, Mike is very upfront about what he does, unlike Brad (though he does a lot). We don't know who wrote which lyrics and it is not a fair comparison to say that Mike is a better lyricist. So I'm discounting lyrics as a part of my influence.
Talent is defined as a "natural aptitude or skill", therefore, Chester DOES have more talent. A talent to me, is something you inherited, not something you can acquire (Nature vs Nurture). Piano (and thus, other instrumental skills) is something you can acquire. I received a performers degree in Piano at the age of 16 (last year) and I do not consider myself to be 'extremely talented', just someone who acquired a neat skill out of practice and dedication.
Chester had a rough childhood and did not receive any musical training in comparison to Mike. I also consider charisma to be one of the most important talents a band can have. Chester shines when he's on stage and he adds a lot of character to the band. I truly believe that LP would not be where they are without his 'essence' in the band.
In short, Mike is a creative genius, but Chester has more (natural) talent.