I have used both on my M5 leather.
In my opinion colourlock cleaner is better than Swisswax - it is in a form of a foam so it is easier to work with. In terms of leather protection leather versiegelung leaves nice mate fininish.
Swisswax milk left a little bit shinner fininsh from what I saw. However still it was very very nice. I read that this type of milk products are moisturising leather, what is not needed in the first 3 years when you use your leather.
Personally - I would go for colourlock clener instead of swisswax. It is simply better. For first 3 years I would go for leather versiegelung to protect the leather. After that time when the leather will be getting less soft, I would use Swisswax leather milk to moisturise it.
