Which is more soluble in water, HF or SO2?
There are a couple different forces at play here. One big difference between the compounds is that $\ce{SO2}$ is much more volatile, with a boiling point of $\pu{-10 ^\circ C}$; in other words it's a gas. It does strongly hydrogen bond with water however, and is pretty soluble at $\pu{94 g/L}$.  

$\ce{HF}$ is also pretty volatile, but much less so than $\ce{SO2}$ with a boiling point of $\pu{20 ^\circ C}$. It also is a more polar molecule than $\ce{SO2}$ and hydrogen bonds even stronger with water. In fact, $\ce{HF}$ is fully miscible with water, so clearly that would be the more water soluble compound.  

To summarize, the water solubility of $\ce{SO2}$ is $\pu{94 g/L}$, whereas $\ce{HF}$ is fully miscible, thus $\ce{HF}$ is the more soluble compound in water.  

Reference for all solubility and melting point data:
 Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.