So I'm tending towards BKool. I like the way it forecasts the gradient for you and tells you when it will change, maybe Zwift does that too but I've not figured out how yet. Also, and this may be the clincher, Zwift seems a bit "gobby". I was riding a route today, just a route not an event, with other people on it when one guy starts texting "Can you lot not speak English? I told you to wait up and let the group come back together". I don't like being told what to do on a real road let alone in my conservatory!!