  We consider a strictly developable simple complex of finite groups
$G(\mathcal Q)$. We show that Bestvina's construction for Coxeter groups
applies in this more general setting to produce a complex that is equivariantly
homotopy equivalent to the standard development. When $G(\mathcal Q)$ is
non-positively curved, this implies that the Bestvina complex is a cocompact
classifying space for proper actions of $G$ of minimal dimension. As an
application, we show that for groups that act properly and chamber transitively
on a building of type $(W, S)$, the dimension of the associated Bestvina
complex is the virtual cohomological dimension of $W$. We give further examples
and applications in the context of Coxeter groups, graph products of finite
groups, locally $6$-large complexes of groups and groups of rational
cohomological dimension at most one. Our calculations indicate that, because of
its minimal cell structure, the Bestvina complex is well-suited for
cohomological computations.
