There are trade-offs all around with digital cameras.

Sony has fantastic electronics, and the F717 has a nifty laser-illuminated focus assist gizmo. However, they force you to use their dorky MemoryStick cards and they don't have any sort of RAW mode (which matters if you want to do serious Photoshop'ing afterward to fix the color balance and adjust highlight/shadow detail. You don't want the camera throwing all that away when it JPEG's the image.)

Nikon has some of the best macro lenses available on this class of camera. You can take a full-frame shot of a small coin, up close. Stellar. However, they don't have any kind of focus-assist lamp, so their low light performance is abyssmal. If you don't care about that, the Nikon 5000 or 5700 are hard to beat. (Nikon just released a major firmware upgrade for the 5000, getting it all the features of the 5700, save the larger lens...) These Nikons take CompactFlash type II, so you can use IBM Microdrives (1GB) or other large solid state cards. When you're saving huge raw files, this makes a big difference.

Canon is my current favorite. I gave my old Canon G1 to my sister, and I'll be getting a new Canon G3 when they're available. You get a reasonable RAW mode, CompactFlash II, and all kinds of other random features. You get a focus-assist lamp. You get better macro than you could get on the older G1, and the G3 has oodles of flash features that nobody else has (e.g., leading or trailing sync flash).

Pretty much the only way to avoid making compromises is to get a higher-end digital SLR, but that's a whole different price range. (And, for hiking, a whole different level of crap that you're hauling around with you.)