Is there any philosophy worth reading?

Yes. I agree with your criticisms - "philosophy" in academia seems to be essentially professional arguing, but there are plenty of well-reasoned and useful ideas that come of it, too. There is a lot of non-rational work out there (i.e. lots of valid arguments based on irrational premises) but since you're asking the question in this forum I am assuming you're looking for something of use/interest to a rationalist.

So my question is: What philosophical works and authors have you found especially valuable, for whatever reason?

I've developed quite a respect for Hilary Putnam and have read many of his books. Much of his work covers philosophy of the mind with a strong eye towards computational theories of the mind. Beyond just his insights, my respect also stems from his intellectual honesty. In the Introduction to "Representation and Reality" he takes a moment to note, "I am, thus, as I have done on more than one occasion, criticizing a view I myself earlier advanced." In short, as a rationalist I find reading his work very worthwhile.

I also liked "Objectivity: The Obligations of Impersonal Reason" by Nicholas Rescher quite a lot, but that's probably partly colored by having already come to similar conclusions going in.

PS - There was this thread over at Hacker News that just came up yesterday if you're looking to cast a wider net.