Medieval 2 was far too vague and bland on the campaign map. Trade agreements were meaningless because everyone let you have them, and the diplomatic options were also kind of pointless given how floaty alliances were. What annoys me the most however is how almost the entire map is grey rebels that don't interact with anything, they just sit there to be conquered.
In Empire you could actually see what was being traded to where and make proper decisions about which trade routes to blockade. Despite several gamebreaking bugs I've played way further into campaigns in Empire than Medieval 2, despite the fact that I've owned the latter since it's release. There was so much more to worry about in the lategame than in Medieval 2, or for that matter, Napoleon or Shogun.
I don't understand why, after Rome II came out, everyone started praising Medieval 2. Go back a few years and everyone was complaining about how bland and unbalanced it was. The battles were a clunky (by design, according to the code) step down from Rome 1, and the campaign was a boring slog through 500 years of apathetically represented history. Some of the mods were pretty cool (played a lot of Broken Crescent; makuria str0nk). but I haven't played it properly since ~2010.