Lexus is the lowest-cost luxury brand to own used. They're built on Toyota platforms - the RX shares its drivetrain with the Highlander, the ES with the Camry, the NX with the RAV4. That means Toyota-level reliability and parts availability at luxury-level fit and finish. A 4-5 year old RX 350 with 45K miles typically retains 65-70% of its original MSRP on 252 lots. The ES depreciates a bit more, but both will run well past 150,000 miles without major work if maintained.
The tradeoff is that Lexus holds its value stubbornly. You won't find the 50% depreciation you see on German brands. A 4-year-old RX costs about 65-70% of its original MSRP. You're paying more upfront but spending less on repairs over time. The GX is built on a body-on-frame truck platform (shared with the Toyota 4Runner/Land Cruiser Prado) and barely depreciates at all - a 5-year-old GX sells for nearly what a 3-year-old one does.