Can't speak for the others, but here's Sofia's situation(at least from my experience):
- don't know about schools, but kindergardens are a privilege you'll be fighting for
- it's fairly safe, obviously exercise common sense
- the metro is great, but it only covers part of the city, the rest of public transit ranges from ok to abysmal, but if you pay for a year, it's cheap as hell too. But I've certainly had no need for a car, so it's doable if inconvenient at times.
- cycling infrastructure is horrible, and there isn't enough of it, but it's there at least and I don't think it's stopped anyone who wants to cycle
- Parks are fine, plus there's a mountain here, so if you need green, you got it.
Other factors you might want to consider:
- air quality and traffic are horrible, especially in winter
- night life is fine
- you can find good food, and you can find cheap food, and if you look, you can find good cheap food.
- gov healthcare is bad, but if you're in tech, your employer might give you additional private insurance, so it's not something I've had to worry about.
- taxes are low
- alcohol is cheap and there are no ridiculous "no sale of alcohol on Sundays or after 10pm" rules some western countries seem to like :).
- tech scene is active so if you want to hang around with techies, you won't be bored
- cheap marginal space is very much available if you don't want/need a glossy hip office in a nice location.
Personally I love it and it's main advantage is that although it's much more expensive than the rest of the country, it's still cheap as hell. I don't make much but I save a lot, I could probably afford to work only every other year if I was frugal enough. I did consider moving for the north-west a while ago, but I did the math and...yeah, the up in purchasing power would be there, but not enough to justify leaving. I still might do it just for the novelty and experience at some point.