Four ways to typeset matrix transpose:

\begin{gather*} A^\mathrm{T} = A^\top = A^\intercal = A^\mathsf{T} \\[2ex] \vec{v}^\mathrm{T} = \vec{v}^\top = \vec{v}^\intercal = \vec{v}^\mathsf{T} \end{gather*}

Subjectively, the last one looks best.