Good read.
http://headfonics.com/2011/05/dynamic-vs-orthodynamic-vs-electrostatic-which-is-which/
On average, electrostats and orthodynamics are better, but mostly because there aren't really any cheap ones. For example, the HE-400, which is probably the cheapest orthodynamic on the market right now costs around $400, while the cheapest dynamic costs about $0.50.
They are different technologies with different strengths. I think electrostats are the preferred type for Summit-fi, but between ortho's and dynamics, there's no clear winner. It depends on your preferences.
I'm personally an Ortho fan though.
EDIT: The T50RP is most likely the cheapest modern ortho at $75.