Based on the cars you have owned previously, it appears that you like upscale (Acura, Lexus), sporty (Acura/Honda) and comfy (Avalon) cars. One car that comes to mind that I think you might like is the 2012-present Hyundai Azera. It is larger and more distinctive/attractive-looking than the Sonata, very comfortable (competes with Impala, Avalon, Taurus) and has fairy strong performance from a 293hp 3.3L V6. You should be able to find a 2012 and possibly a 2013 for under $20k. I've retned these on several occasions and I would have no problem buying one. They're great cars that get easily overlooked being stuck between the Sonata and Genesis in terms of size, class and price.
Another possible alternative is the Nissan Maxima. You can find 2014 models for $20k or a little less if you're willing to search. They're attractive, comfortable, strong performers and you don't see a dozen of them every time you go out.