Jeep Grand Cherokee Weak Spots

We are looking to buy a 2nd or 3rd gen Jeep Grand Cherokee (1999-2010).

What are some of the most reliable engines/drivetrains on these GC models and what are those that's better to stay away from?

Also what are the weakest points, parts we should be prepared to replace after the aquisition of a GC with at at least 200K miles on the clock.

Thank you!