EG and Speaker are basically the same book, the latter written before but published immediately after the former, so they pair up nicely. As a Trek fan, though one always disgusted by the "Prime Directive" and its parallels in a lot of Sci-Fi I really enjoyed Speaker's disassembly of that concept. After that, well the Shadow series has the benefit of Card becoming a more experienced writer but even Ender's Shadow didn't really fit for me, though it was a good book. The others are fine but they don't really fit the series IMO

Yeah, big gap between the two, I read them in roughly publication order except the Shadow Series which I didn't know about till the last book came out, big out of sequence read which might have damaged it for me, but I consider the series fairly weak.