Ok Erik, here is my answer: NONE.
I agree with Ronthepon.
By my calculation, you are more likely to spin a zero straight away than achieve ANY chosen number of consecutive non-zero spins. (This answer applies to both to a single-zero and double-zero roulette wheel).
In second place, my answer is ONE - you are more likely to achieve just a single 1-36 spin than any other number of non-zero spins. Again, I agree with Ronthepon.
In other words, I'm saying that if you compare any two figures of consecutive 1-36 spins, you should always bet on the smaller one.
NONE is smallest figure of all.
Many will find this unbeleivable!
Simon