Like Tim, I think both BW and colour have merits and that some subjects are better suited to one or the other. But I do have a preference for those subjects that are better suited to BW ... reasons below. It may not even be so much a preference as a prejudice ...
I was just looking at a close up shot of a poppy in full bloom shot wide open with a digicam. It was a well seen shot, with only the flower head in sharp focus, and the stem and leaves blurred out by the shallow DOF. The strong red flower set against the more subtle oranges and greens of the background worked nicely - just three colours in the entire image. It would have been slightly interesting, but largely pointless rendered in BW. The colour was a major aspect of the intent - the forms seem less relevant.
The problem with colour in photographic images seems (to me) to be that it must exceed reality for it to be interesting, and that requires either the sweet light of dawn or dusk or some special quality of saturation that stems from the emulsion (Velvia) or from filters. A while back, I got hold of a book by Bob Krist (a wiz of the National Geographic) - natural colours were out (this was the 1980's) and it was all warm-ups, polarisers, and fill lights to create the images he wanted. These days, subtle desaturations in PS are also popular. Somehow, if a colour image doesn't go beyond the excitement we can remember (or imagine) it may well be considered snapshotty or little more than a record shot.
I'm personally much more interested in form and line than in colour for its own sake, and I'm also more interested in tones than in shades. Maybe this is down to the magic-of-silver ... the sense of intrigue stimulated by watching old black and white movies, by old newspaper or family photos. I've noticed sometimes that when I look at images of stonework in colour taken in ordinary light, I don't really
see the shades of sandy browns or the subtle differences in the speckles of algae. It's only when the image is translated into BW that the strength of each adjacent tone is declared - each tonal difference implying a distinct form. In the absence of some significant colour, our eyes seek out forms, lines, or texture ... and quite often what would be a mundane colour snap becomes iconic in BW. Tim's standing stone seems a good example of that.
While the aesthetics of a colour palette may depend on the quality of the light or its temperature, in a BW image light exposes or masks forms through its relative strength or diffuseness. This was something I Iearned when working in relief sculpture. And any light will do (almost) since each degree of light (by strength or direction) will have its own specific effect. Strong forms dissolve in a diffused light, gentle forms can be made striking under a harsh raking glare ... and the contrast can be manipulated to some extent. I guess this last point is one of the challenges that I find most exciting in BW photography.
The last thing I'd want to suggest is that there are rights and wrongs in this, but I wanted to put forward some of the reasons why I prefer strong forms and naturally gravitate towards BW, while also hearing how others feel about their own choices.
I'd better get back to work.