There are really 2 choices for reliability: the Lexus RX350 and the Acura MDX.  Test drive both and see which you like, but just realize the Lexus is better engineered than the MDX for longevity;  the Acura MDX has the 3.5L V6 engine with cylinder deactivation that can potentially wear out/damage the engine over time.  Also, the engine is direct injection-only and susceptible to carbon buildup overtime.  The Lexus has neither of those shortcomings, and if you plan to keep for a long time and put lots of mileage on it - I say stick to the Lexus.  But if you really like the other choices, just lease a newer one under warranty and return before the warranty expires.

Forget the Audi, bmw and benz unless you have money burning a hole in your pocket. Repairs for these cars are stupid expensive. Especially the benz. Stay the heck away, it really isn't worth it despite how cheap or enticing the price point is. There is a reason it is THAT depreciated.

My top picks in order would be the lexus, volvo, acura. If you looking american then caddy would be ight from my experience. Life is less than the japanese cars but seems to go okay. 

Of course the best would be to make sure that the cars are in good condition and not just a dealer wipe down. Get an inspection done as well as it will be well worth it. Might seem like a good buy but have a problem that you can't see without actually lifting up the car.

In terms of "most reliable" here is my ranking from best to worst:

1. Lexus RX (known for their reliability)

2. Acura MDX (relatively reliable except for their newer complicated transmissions and technological engines with cylinder deactivation...)

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3. Volvo XC90 (not nearly as reliable as the RX or MDX but still better than the Audi, Mercedes, or BMW)

The Cadillac is a joke

I would give the RX a test drive and see if you like it. Keep in mind the RX is more luxurious while the MDX is more sporty but also very premium.

Acura and Lexus are the only two worth checking into.