I get absolutely giddy every time I see MVC2 boot up on my cab, however, there's an important thing to consider... There are about 120 million PS2s out there, so if one breaks while it's inside your cab, no-one is going to cry. However, the Dreamcast went out of production after only 2 years, so they're in considerably less abundant supply. Really though, you can do whatever you want with your own property, so it all comes down to which game you want to play more (and with Tekken 6 right around the corner, I think that MVC2 may have more longevity since it's a modern classic).