Blindsight (and the excellent sequel, Echopraxia) is indeed great.

Solaris by Lem is perhaps the one above all. Lem wrote several of these "inscrutable alien first contact" novels: His Master's Voice, The Invincible, Fiasco, and Eden are basically all variations on this theme, each one unique and highlighting a different aspect of humans' inability to understand the universe. The last three are a little dated now, but still enjoyable to read. HMV is rather dry, a Borgesian essay on an investigation into an alien signal, with lots of references to fictional scientific papers. (Len also wrote two collections of very Borgesian essays that are basically reviews of fictional books: A Perfect Vacuum and Imaginary Magnitude. They're interesting and funny, but I wouldn't put them among his most entertaining work.)

Roadside Picnic by Arkady and Boris Strugatsky is also a masterpiece. They also have a few stories about unseen aliens manipulating the history of humanity by placing traps or transforming humans into infiltrators. The Max Kammerer books (e.g. Beetle in the Anthill) involve this storyline and are very good, probably not well known today.

I tried Tchaikovsky (both Children of Time and Shroud) and found him to be completely unengaging as a writer. Just really dull writing and flat characters. Watts and Reynolds are much better writers. Watts in particular can really pack a punch.