Which game is the most stable?

If I were to specialize in playing one particular game which one looks to stay stable? It appears like the single and double deck games are changed the most with things like 6 to 5 payoff and fake double deck.

Is six or eight deck more stable or do games that the dealer hits soft seventeen more stable than the ones where the dealer stands on soft seventeen? I would just hate to practice one game and then find that opportunities in it are dying off.