BURMESTER B99 OR VANDERTEEN 5A'S

compared to your ML's? different , but not 'better'.

The most expensive and more exclusive of the two is better by definition. I have personally only heard the Vandy 5A's. Burmester isn't carried by anyone local who doesn't demand your net worth and credit worthiness first.
I refuse to do business with him niether he nor I give one perfectly spherical rabbit turd for the loss. Did you ever wonder how those rabbits do that? Better yet why manufacturers flock to the insane dealers.
I can't afford a Bentley, Rolls, Aston Martin or Lamborghini but the dealer is always pleasant and treats you like a person. I happen to own a decent driver's car perhaps that is the reason. Otherwise it isn't any more than 15-20% of the cost of cheapest model of that group.

better in what way?

Burmester is heavier..other then that the Vandys have it all

Radrog: You will get a better response if you give some indications of what you expect from a speaker. What music do you listen to? What amplifier do you plan to use? What size is the room? What are the perceived shortfalls of your current speakers? How much do you want to spend?