Congratulations on the new house! I’m sure you have a lot of exciting projects ahead. 
As far as your questions, I’m sure you won’t be surprised to hear that there’s no one right answer. It depends on a lot of different things, including the amount of technical tinkering you’re willing to do each week, your financial budget, what country you live in, how complicated you need your Home Automation rules to be, what type of phones your household has, how often your local Internet goes out etc. (for example, if you have all Samsung galaxy phones, then smartthings has some additional features which can be nice.)
I agree that smartthings is not The best platform for a mostly Z wave set up right now. So at the time of this posting, if someone is mostly interested in z wave, I am recommending some other alternatives. Why don’t you start by reading the following: