It depends on which features are more important to you.
More megapixels? Optical viewfinder? Slim size? The Casio Z750 has an impressive 7.2 megapixels and 2.5'' LCD and slim design but lacks an optical viewfinder. The Fujifilm is very small, 5 megapixel, and an ISO up to 800. Again, no room for optical viewfinder though. I believe the Canon is the most expensive- 7 megapixel, 2'' LCD, high speed movie mode and some funky features like skin tone lightening or darkening and color swapping. Have you ever considered a Nikon 7900? It's a fairly small 7 meg, 2'' LCD and optical viewfinder. Uses SD cards. About $379.
I am looking to buy a new digital camera and i dont want to spend more than $450 but i do want the best camera for my money. After alot of research i have narrowed my choices down to the Fuji z1, Casio z750, sd500, and nikon s1. I am leaning toward the casio and possibly the fuji. I was wondering if anyone has one these cameras or has compared them, and could help me make a decision.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic