BMW has a long history of making great cars. Here are some of the strong points of the BMW7 Series:

The best feature of the BMW 7 Series is its looks. 
A classic but modern take on the BMW style.
You'll appreciate it for its subtle details like its leather interior work and tasteful features.
A roomy interior design.
Smooth rides thanks to a fully redesigned transmission.
A variety of engine options including a V-12 on the highest-end model.

Lexus often bridges the gap between performance and style. Here are some of the best parts of the Lexus LS 500:

The best feature of the Lexus LS 500 is its ride quality.
It is designed to give you the smoothest ride possible.
Equipped with improved suspension systems and cabin design. 
Exceedingly quiet cabin in all conditions.
The interior is designed with a luxurious and artistic aesthetic. 
The materials are tastefully chosen and arranged for a unique look and feel. 
The quality of the build is exceptional in every way. 

The Mercedes-Benz S550 is filled with performance and luxury technologies to make driving effortless and safe.  Here are some highlights from the Mercedes-Benz S550:

One of its best features is the Magic Body Control system. 
It uses a stereo camera to look for changes in the road ahead. 
The body and suspension cancel out many of the bumps that you would normally feel. 
The Mercedes-Benz S550 is also able to help you drive using automated driver systems. 
One button to have your S550 switch lanes for you. 
It is one of the closest options to a self-driving car that you can get.

Each vehicle is unique and offers its own benefits. The Mercedes-Benz S550 uses technology to make driving much easier. If you want help on the road to make your driving safer and more relaxing, then it is your best option. If you want a car that looks like a luxury vehicle in every way, choose the BMW 7 Series. Its styling and quality can help you impress others without needing a lot of extra frills and flare. If you want the best ride quality possible, then the Lexus LS 500 is your prime option. Its ability to handle rough roads while staying peacefully quiet is a big advantage for anyone that wants to relax and enjoy every trip. 

All three of these cars are great options but for different reasons. Stop by your local dealer to test all of these cars. Seeing what they can do in person is the best way to determine which one is right for you.