It seems no one has an opinion on this. I'll reveal what info I found out in case anyone else is wondering.
The only two I really checked out were CVF and Holley. CVF is very similar to March and some other brands. CVF uses a 1990 Corvette water pump. They state they have have a lifetime warranty on their water pumps. The downside I have seen is that if you have to get to the water pump, it involves basically removing everything. Their main bracket covers the entire front of the motor and must be completely removed, along w/every other accessory if there's a problem w/the water pump (or maybe another other accessory as well)
Holley has a limited warranty on their pump. But, it's an LT type pump. The replacement impellor is about $70. If it fails, it basically involves taking off the belt and 5 or 6 bolts, replace the pump impellor, bolts, belt and you're back in business. No need to remove obstructive brackets or other accessories. All accessories bolt individually to their pump.
I went w/the Holley. I've ordered it, but haven't received it yet. It just seems like much less of a hassle for servicing and the Holley brand is probably not going away any time soon. Can't say that with as much certainty regarding these other companies.