Rank feature selection over multiple datasets
An easy one to try would be average ranks, where you take the mean of the ranks for each feature. For your example, 

$
\begin{array}{cc}
  \textbf{Feature} &amp; \textbf{Avg. Rank} \\
  1 &amp; 1.5 \\
  3 &amp; 2 \\
  2 &amp; 2.5 \\
  4 &amp; 4 \\
\end{array}
$

You could also weight the ranks by the size of the dataset, if the datasets that you are testing on are not the same size.