Both are beautiful, but the B&W is more compelling to my eyes. Having said that I spent some time trying to understand why I reacted that way to the two photos. The colour seems limpid due to its warmish-green hue; the B&W is "colder" which, to me, makes it more in balance with "water". I think I also have something against brownish-looking water (due to the stream-bed and algae there, not your photography). I find the same is true in my own work - I am most likely to convert to B&W when the stream comes across "brownish".
Thanks for sharing.