  The light-front wave functions of hadrons allow us to calculate a wide range
of physical observables; however, the wave functions themselves cannot be
measured. We discuss recent results for quarkonia obtained in basis light-front
quantization using an effective Hamiltonian with a confining model in both the
transverse and longitudinal directions and with explicit one-gluon exchange. In
particular, we focus on the numerical convergence of the basis expansion, as
well as the asymptotic behavior of the light-front wave functions. We also
illustrate that, for mesons with unequal quark masses, the maxima of the
light-front wave functions depend in a non-trivial way on the valence
quark-mass difference.
