I would get Ecobee
You can add zones
All Nest has is that "wow" factor. I just got my downstairs HVAC redone and all they had was Nest. When I do my upstairs I'm definitely getting Ecobee
What's the point of adding thermometer zones if your HVAC not set up for it? I can see being curious of a random room in your house but it doesn't matter if your HVAC zone is for the whole floor anyway. Or am I missing something?