Assuming you're looking at that Willard 30 cutter in Ventura on Yachtworld.com... There will be no comparison performance wise - I'd expect the Cat36 to outperform the Willard, esp in light airs (but haven't actually sailed one) Close quarters handling will be much more difficult (docking, esp in reverse) maneuverability will be way down with the Willard too.
But from the pics (if they're recent) the W30 looks very well cared for and well equipped.
Comparing these two boats is not an apples-to-apples thing... a "character" boat such as the Willard is usually bought by someone in love with the look of that type. (or hooked on full keeled boats)
Both boats are similar lengths overall, so the moorage cost will be a saw-off (but then you're buying the slip anyway)
If you don't plan to leave the dock much or don't hope to do some light air daysails etc, it's won't matter - get the one you really like best.. If on the other hand there is a lot of daysailing and weekend cruising in your plans a Catalina (or similar) might better suit.
Don't forget that the Cat 36 you're looking at is not the only one on the market!