Wide Angle - LX3 better
Hot shoe - LX3 has, S90 doesn't but honestly - which one of my cousins use external flash
Video quality - LX3 better
Macro mode - LX3 better = 1cm (S90 = 5cm)
Sensor size - LX3 better 1.63 (S90 = 1.7)
Optical zoom - S90 better
Size & weight - I prefer S90
Price - S90 cheaper by S$10 only
Noise reduction - Although S90 better but this is compromised with detail so I guess this one both same lah
As you can see, LX3 wins in so many aspects compared to S90. But it's 2 years old whereas S90 is 1 year old. And usually it feels nicer to buy something newer. I was really in a dilemma but eventually decided on the Canon S90.
My camera's 'Color Accent' scene mode. I love it!