The Canon S2 has one of the best macro modes available as far as getting very close. Dpreview says you can actually touch the lens to the target and still get an in-focus shot in super macro. It is also pretty exceptional for macro shots zoomed out, being able to get an area 8.5 cm across at full zoom from 70cm away. That really helps for light and flash use, as well as makes for a much flatter and less distorted image.
http://www.dpreview.com/reviews/canons2is/page5.asp
The articulated LCD would also be great for macro if you had the subject higher than knee level or wanted to use the zoom.
The H1 is almost as good for close distance and probably more versatile in the ranges you would want to use for a large insect. It is almost as good at zoom also.
http://www.dpreview.com/reviews/sonydsch1/page5.asp
They are both good. I would think you would want to use them at zoom so you don’t block light and can use flash if you desire. And avoid extreme barrel distortion you get from close at wide angle. They will both just about fill the frame with a big mantis at full zoom, which is unusual. Most other cameras don’t do well in macro at zoom. It seems the S2 LCD would be more versatile. But the macro range at wide angle from up close is more versatile with the H1.