You can enjoy VSM as a traditional LLM road to glory save, 5th tier to trying to win the Serie A/Champions League, and have the national team building in the background and as something to work towards after you complete the club side of things.
SM League is different, you will be gruelling in the qualifications for Europe for a long time, trying to build up league rep, and getting the club professional etc., but I find that after long enough the league becomes a bit of a doddle and is just a timesink whilst you are waiting for European games to occur. But the end payoff of winning a European title with a team from the SM league is obviously much greater.
It depends on what you like and what you are looking for.