Tough call. I would say any 2006 to 2010 that has a V8 which, of course, is against conventional wisdom here. I have a 2007 V8 - the only thing I know about the V6 is what I read here but it sounds pretty bad engine and transmission wise to the V8. My timing components are holding up well at 120K+. My 6R60 responded very well at 100K to a proper pan drop - filter change - and the proper attention to fluid level afterwards. Yeah - I lost a follower but fixed it cheap. It's not like Ford is the only company using roller rockers on overhead cams.
There is no way I can emphatically prove this - but if you can score a V8 with maintenance records then you are likely good. Oil pressure matters so much on how these 3V engines work that history matters a lot. I bought mine a year old with 17K as a CPO. So I've been in charge since it was practically new and while it's been challenging at times, it's been manageable.
At the end of the day, everything changes when you buy any vehicle with 100K. Anyone can destroy a vehicle in 100K miles.
The 09-10 use the 6R80 Trans, which is from the F150. All the bugs were worked out, supposed to be good. But, I looked at an 10 V8 Explorer at a used car lot, 110K or so, the owner said he just rebuilt the trans, he bought it at an auction thinking it was bulletproof. He thinks the prior owners used it for near capacity towing, the hitch was pretty well worn. I think the V8 could tow almost 8k lbs, putting it in base F150 territory.
Still, in this generation of explorer (for the V8) (not so common things that can happen)
-The 06 v8 transmission seems to have many complaints, but I've driven 2, a mounty and an explorer, they drove perfect.
-There is a tsb about the cam followers, one can fail and possibly take out the engine (or nothing)...
-Exhaust Manifolds, and it is a difficult job, I've seen a few with this problem.
-Cam phasors (not very common on the 4.6, but it does happen). Again, the used vehicle thing, oil changes, etc.
-Radiators (not such a big deal)