Did you know that Infiniti is made by Nissan? Also, Lexus is made by Toyota and Acura is made by Honda. Their cars are very related to each other. Old Lexuses, Infinitis, and Acuras are the most reliable luxury cars and they were quite nice to drive, but I'll find some other cars. I would avoid BMW because even though your dad does your maintenance and you had a good experience with your BMW, most of them become money pits after 70k miles. That is why their values plummet when they role off the dealer lot. Mercedes is the same way, but they are slightly less expensive to maintain, which isn't saying much.
I don't know if the Toyota, Honda, and Nissan badges bother you or if it is the brand. If it is the brand, Lexus, Acura, and Infiniti are out as options since they are owned by the companies you don't like. If you are fine with them, the Lexus IS is reliable and offers a sportier driving experience. The ES350 gives you more luxury and quietness, but it is not sporty like a BMW. The GS is more expensive and I don't think you should consider one because they are more expensive and overkill for your needs. The Infiniti G25 and Q40 can be found for DIRT CHEAP. They are also nice, reliable cars that nobody talks about anymore. I think the Infinitis are some of the best used car deals today. Infiniti has really gone downhill since they made this car. The Acura TL should also be considered. It offers more space and a nice powertrain. It has been pretty reliable. If the TL is too expensive, look at the TSX. Less expensive and is basically an upscale Accord.
For the brands you haven't knocked off, you need to look at the Kia Cadenza and Hyundai Genesis. The Genesis is really nice and is available with 3 different engines. Both of them can be found for cheap because they don't have a prestigious badge. If you buy them CPO, you'll get the remainder of the 100k mile/10 year powertrain warranty. They are underrated luxury cars.
Some premium feeling mainstream cars include the 2014-2017 Mazda6, 2015-2018 Hyundai Sonata, and 2014-2018 Kia Optima. The Mazda has a lot of road noise, but a nice interior with many available options. The Kia is probably the best though.
There are several people here that only recommend American cars, so be ready I guess.
I can find some good cars in your area if you could provide your zip code.