For my personal taste, it would be ES350, then IS350, then TLX. 

If you value luxury as a first priority, I think it would be ES>IS>TLX

If you value sportiness as first priority, I think it would be TLX>IS>ES (or just get a GS)

If you want a mix of both luxury and sportiness and reliability and don't need a people hauler, IS>ES>TLX

If you want to have a good amount of space plus the factors above, my first ranking applies.

If you care solely about how long they will last, the ES and IS would trample the TLX. 

The TLX is more modern and you might like it more (thats a personal choice), but Honda compromises on longevity for modernizing their luxury division.

Personally I would just swing for a GS before the new ones are gone for good. Out of the choices you listed, the IS350 is appealing but its too small so I would get the ES. 

To be completly honest, I wouldn't buy any new car especially a luxury one.

What are you looking for exactly - best in terms of what?  For most longevity it would be Lexus ES > IS >>> Acura TLX

They are all great vehicles, and the other comments have it spot on.

The TLX and the IS used to be direct competitors, but it seems the TLX is a bit larger these days.  And the TLX doesn't quite compete with the ES because the ES is larger.  These cars seem in all different categories IMHO.

From smallest to largest: IS, TLX, ES.  That's just size.  Personally, I like smaller to medium cars because finding parking is a PITA, and I can fit smaller cars into more spots.  But that is a circumstance of my city.  If I lived in another city, I would probably get the bigger one.  

With that said, when I have a hard time deciding between top contenders, I usually fall back on look and feel.  

Which car looks the best to me? Which car drives the best for my liking?

Give them a test drive and see which you like.