The Daley Han Solo adventures top all for me, but are they fully considered EU?
Thrawn trilogy, Han Solo trilogy, Dark Forces arc, Splinter of the Mind's Eye, Shadows of the Empire, Courtship of Princess Leia, Hand of Thrawn
as far as the prequels go:
Jedi Apprentice, Jedi Quest, Shatterpoint (yeah! Star Wars meets Apocalypse Now!!), Last of the Jedi.
I also quite like the "Tales from ..." books.