It depends on a lot of factors: how is the coverage in your area? Can you live with the phones that are available? Do you want 3G or 4G LTE coverage (which comes back to the coverage in your area)?
Metro's LTE is good in some places and not so good in others; it all depends on the spectrum that they have available in the area and I'm not at all familiar with what's what. I have seen people posting good speed tests in the Dallas area, since that is where I'm at that is what I pay attention to. The 3G is pretty decent here in the Dallas area as well.
I think that I've read some other posts saying that VM's 3G coverage and speeds are a lot better than what MetroPCS has.
Basically, Metro is great for my wife and I; we live in the Dallas area and have great coverage and 3G speeds (don't have an LTE phone yet). I love the truly unlimited data, talk and text. I have no caps and my wife and I are only paying $45/phone/month.
Hope this helps ya.