Why INTP for Kant? Kant was incredibly organized very driven. His writing and what we know of his life strike me as very INTJ.
ENFP sounds very reasonable for Plato though.
i don't believe he was dominant intuitive. his beliefs (and his ways of exercising them) remind me of traditional INXP behavior (considering his way the most true and judging everyone else for being wrong). i credit INTJs, perhaps wrongly, for being better than that. in addition, the contrast to ayn rand's philosophy is entirely antagonistic, and i consider rand to be a prime example of INTJ.
i hunt INXPs for bounty
FUNCTION ORDER FOR THOSE THAT CANNOT UNDERSTAND WHAT ENXP MEANS: Ne > Ni > Fi=Ti > *
"Just as Darwin might possibly represent the normal extraverted thinking type, so we might point to Kant as a counter-example of the normal introverted thinking type. The former speaks with facts; the latter appeals to the subjective factor. Darwin ranges over the wide fields of objective facts, while Kant restricts himself to a critique of knowledge in general."
Arthur Schopenhauer - 5w4 SX/SO INTP ? Very unhealthy one
Hegel - 5w6 SO/SX INF/TP (maybe INTP, loads and loads of Ti)
Marx - 5w6 or 6w5 INTP
Satre - 5w4 so/sx INFJ or just a weird INFP or INTP
Hannah Arendt - 5w4 sx/sp? maybe an so/sx INF or TP
I would agree with your placement of Hobbes and Nietzsche, though eh I'm rather sick of the Nietzsche fanboy-ism,he wasn't that great :/
These are good
Also, I think Nietszche is popular because his writting is very appealing and has excellent style, and his philosophy is often a lot 'cooler' then the that of most other philosophers, with all the 'Ubermensch' and 'Will to Power' stuff.