Looking at two Suburbans to buy, need opinion

You speak common sense here.. One of the red flags with the black 2009 Burb is that the owner said he only drove it 40 miles after the rebuild, which is very strange. If he did it for himself, he would have put a lot more miles on it since the sprint.

He also said he got it for a song, with the blown engine, not sure the specifics of that.
It means the previous owner got told it needed a new motor because the mechanic they took it to was to dumb to know how to diagnose and fix the afm and oil usage issues these had or was going to rip them off by doing the afm fix and charging them for a replacement motor.

After having good and bad experiences with the 2007 to 2013 body style and being around several of them, I wouldn’t consider anything with a vin that starts with 3 or has higher than the LT package.
Find a ford f250 or expedition. For that money there are better deals. The gm stuff is a bigger risk between engine and trans problems.