Does anyone have a preference between Superpolator or UFOstretch? Does anyone use both? Just curious, looking into both right now.
They are very different tools. UFOStretch is for modifying subsets of characters by scaling and interpolating on a single axis. It is useful for tasks like creating small caps and figures. Superpolator is a multi-axis interpolation tool that's mostly useful for interpolating and extrapolating entire fonts from an arbitrary number of master fonts.
Have you also looked at Font Remix Tools? Worth a look.