In my opinion, with manual you will always have better control in snowy conditions. Steptronic does give some more options and helps a bit but is not the same as manual. Here are my observations based on mostly my previous manual cars and my current one and only (and the last) automatic X3.

Manual does not downshift unless you do it. That can sometimes make things confusing on slippery conditions with auto tranny when going up a hill or pulling a trailer etc. and suddenly it downshifts when you least expect it. X-drive in X3 helps a lot to get over this and not loose control.

You can control the car a lot better with just applying more or less gas because of not having a torque converter and the delay in transmitting the power.

Engine braking with manual is an advantage. You can use that when coming downhill and don't need to brake in corners to cut your speed etc. Steptronic does help a bit but not that much. Also I find downshifting with step be a bit harsh and not as smooth as with how I do it with manual.

Steptronic does not shift when you tell it to. It may rev another 1000 after you tell it to shift when accelerating. When using engine brake to slow down you cannot skip gears since it goes through every one and thinks for a while before the next move. With a manual I can shift from 6th to 3rd if I feel like it.

Conclusion... I just find manual more flexible to different situations and having better overall control. At the same time I also understand how frustrating a manual can be in a very heavy city traffic.

My vote: Manual. Maybe 20 years from now, automatic.

- p