i LOVE hardie. they have it in smooth or with the wood grain. both look nice depending on the style of the home. it NEVER mildews or gets dirty etc. it's great!

I've never heard of RealSide. it may be a good product, but I'm certain that you can't go wrong with hardie. the contractors here are very pleased with it. it's very popular in South Louisiana

It is always difficult to find out how these products are made but I think RealSide is Spruce-Pine-Fir grade wood with a factory applied Borax containing primer and finish paint to make it an acceptable substitute for cedar clapboards at a lower cost. Of course, it's only as good as the process used to make it.

It's certainly worth researching, especially for the person installing it.

I've never understood why imitation wood clapboard siding would have a simulated wood grain. Raised grain in real wood clapboard siding would be a sign of lower quality and could even encourage the growth of fungus/mildew in some climates and exposures.