I've never played any of the Star Wars RPGs, but I love the West End Games books. Especially before the PT, they were my go-to for Star Wars lore. Of course, much of their information is considered inaccurate now anyway (like the size of the Executor, for starters), but they were such fun reads and really added so much depth to the Star Wars universe. COMPNOR, for instance, while hardly mentioned in even EU sources, is a fascinating branch of the Empire than brings it closer to Nazi Germany, and entirely conceptualized in these books.