Personally, having worked for a company who install both Hive and Nest, I did a lot of looking into the pros and cons of each for my situation (pre-ST) and the Hive won. I didn’t need the learning of Nest, as there was nothing to learn - I don’t have a household routine which seems to be the thing Nest brings to the party, you don’t have to program it in the traditional sense as it learns from people coming home at 3pm, the house being empty from 9am etc.
If that routine based home describes you, then Nest may be better. But read on.
I then had a bit of regret when I got ST, as Nest seemed to be supported out of the box. Alex changed all that and the support for Hive seems to be perfect as far as I can see - I can do everything I need to via ST or my SmartTiles dashboard running on a state of the art Blackberry Playbook (!). It naturally integrates into my rules - originally though RulesMachine, but now CoRE.
So whilst Hive needs programming (don’t be fooled by the geolocation stuff, it’s pretty poor), it suddenly becomes 100 times smarter with ST, and the advantage (to me) of Nest is lost.
I rarely use the Hive app and I think that’s the best thing about it being supported, I don’t want to be using half a dozen apps. My Hue and Hive are both controlled via ST.