I would go with the Lexus ES350, it’s based on the proven Toyota Camry/Avalon platform and also 3rd year in that generation;  also, they tend to last longer than Acura luxury cars.  Meanwhile, that Acura is first year in that generation (always good idea to avoid beginning of generation to let any issues get sorted out), but the bigger thing is say you got the 2.4L I4 engine, well it is mated only to the 8-speed dual clutch transmission- for longevity stay away from dual clutch (can be very expensive to repair/replace if there’s issues;  the Lexus 6-speed regular automatic is more proven).  Then if you got that 3.5L V6 engine - first off, it comes with cylinder deactivation (or what Honda calls VCM) and can overtime potentially wear out/damage the engine if you don’t disable it (you can only disable via the aftermarket);  since you would buy used, odds could be the previous owner(s) did not disable it and so then you are at the mercy of them being on top of the engine oil change intervals since the VCM needs clean oil to operate properly.  Even then, depending on the mileage you wouldn’t necessarily know how much wear the engine has sustained.  Also, that engine is mated to a 9-speed automatic transmission which has been problematic and subject to class-action lawsuits (and that model year TLX was the first year to use that transmission, so even worse as it invariably will have more issues.)  Personally, and for longevity purposes, I would be weary to own that 9-speed transmission.  Finally, either Honda engine is direct injection only and, over time, can be susceptible to carbon buildup on back of intake valves and may need periodic cleaning of the back of the valves:  catch can recommended to mitigate the issue but still may require periodic cleaning.  Whereas the Toyota engines come with both port and direct injection (clever system) and the port injection portion manages to spray gasoline on the back of the intake valves thereby cleaning the gunk off.  Between the two, and if you plan to keep for a long time, no question the Lexus has a better chance to last longer.

https://www.carcomplaints.com/Acura/TLX/2015/

https://www.carcomplaints.com/Lexus/ES_350/2015/