ConText looks pretty good, but the formulas seem rather verbose with

    \placeformula[eqn:famous-emc]
    \startformula
         E = mc^2
    \stopformula

Compared to the quick an dirty latex:

    /[
        E = mc^2
    /]

Granted, with references in latex you'd need something pretty similar

    \begin{equation}\ref{eqn:famoues-emc}
         E = mc^2
    \end{equation}

I must say that the \begin{env} and \end{env} feel better to me that \startenv and \stopenv. Simply because it differentiates the environment name better.