The problem is, ST and OW bagged the only two airlines in the country that looked at least half fit to be in a global alliance. Everyone else is too small and disorganised or operates on a different business model (UN).

Back to the OP, that probably depends on where you are or want to be in Moscow and StPete and how much luggage you carry. With the cost of getting to the airport in Moscow planes and trains cost probably the same. But dealing with security and navigating SVO or DME or VKO can be stressful enough so I'd probably take the night train anyway.