  The molecular-to-atomic gas ratio is crucial to the evolution of the
interstellar medium in galaxies. We investigate the balance between the atomic
($\Sigma_{\rm HI}$) and molecular gas ($\Sigma_{\rm H2}$) surface densities in
eight nearby star-forming galaxies using new high-quality observations from
MeerKAT and ALMA (for HI and CO, respectively). We define the molecular gas
ratio as $R_{\rm mol} = \Sigma_{\rm H2} / \Sigma_{\rm HI}$ and measure how it
depends on local conditions in the galaxy disks using multi-wavelength
observations. We find that, depending on the galaxy, HI is detected at
$>3\sigma$ out to 20-120 kpc in galactocentric radius ($r_{\rm gal}$). The
typical radius at which $\Sigma_{\rm HI}$ reaches 1~$\rm M_\odot~pc^{-2}$ is
$r_{\rm HI}\approx22$~kpc, which corresponds to 1-3 times the optical radius
($r_{25}$). $R_{\rm mol}$ correlates best with the dynamical equilibrium
pressure, P$_{\rm DE}$, among potential drivers studied, with a median
correlation coefficient of $<\rho>=0.89$. Correlations between $R_{\rm mol}$
and star formation rate, total gas and stellar surface density, metallicity,
and $\Sigma_{\rm SFR}$/P$_{\rm DE}$ are present but somewhat weaker. Our
results also show a direct correlation between P$_{\rm DE}$ and $\Sigma_{\rm
SFR}$, supporting self-regulation models. Quantitatively, we measure similar
scalings as previous works and attribute the modest differences that we find to
the effect of varying resolution and sensitivity. At $r_{\rm gal}
{\gtrsim}0.4~r_{25}$, atomic gas dominates over molecular gas, and at the
balance of these two gas phases, we find that the baryon mass is dominated by
stars, with $\Sigma_{*} > 5~\Sigma_{\rm gas}$. Our study constitutes an
important step in the statistical investigation of how local galaxy properties
impact the conversion from atomic to molecular gas in nearby galaxies.
