Peirce also, along with Frege, independently discovered the existential and universal quantifiers, to name just one major contribution. His existential graphs[1] are extremely cool too. Peirce is grossly underappreciated largely due to the efforts of his less gifted but more politically astute childhood "friend" Simon Newcomb to obliterate his career and legacy. The Peirce gateway is full of great stuff[2][3]. This[4] is the companion paper to How To Make Our Ideas Clear.
Also Richard Rorty. I seem to never agree with anything he says—he always goes too far—but have all his books and find him very stimulating. Hilary Putnam talks in his books about their disagreements, and Putnam always seems to take the more sensible side. Putnam is a very clear and stimulating writer—his Realism with a Human Face is perhaps his best and a good place to start, filled with remarkably good essays.
p.s. Dewey's Art as Experience changed my life. I'm a musician/artist and philosophy student, and it solved all my problems concerning art, which each further book of analytic philosophy of art had only multiplied.
I'm also curious what defines your standard for clear thinking. Philosophy is at a level of abstraction higher than any other intellectual discipline, and to a certain extent it's not possible to discuss philosophy in the way we discuss engineering, for example. It's the difference between relying on assumptions to communicate effectively and attempting to analyze the assumptions themselves.
Peirce's "How to Make Our Ideas Clear": https://courses.media.mit.edu/2004spring/mas966/Peirce%20187...