I would go for the things you can't change. So, if location is good, and the space / size then I'd go for the one that needs work, even if you can't get it all done at once.
Does depend, of course on what needs doing - you need to find out what the wiring is like, how old the boiler is, what condition the roof is in etc. Decor is cheap, but some of those things come in more expensive.
Then it depends if you are able to do some of the work yourselves.
Kitchens are a bit of a 'how long is a piece of string' question.
Also, if you are a young couple, able to 'manage' for a bit in uncomfortable surroundings, or if you already have small dc or if you have a disability or illness, or if you are both already working 14 hours a day to make ends meet, etc.,etc.etc,
On the face of it, the one in need of doing up would seem a better buy. New builds always come at a Premium for the convenience. You will never make any money on a new build but would be able to on a doer-upper. Howver, the reason they come at a Premium is you don't have weeks or months of discomfort whilst you get work done on them, and a lot of people like that,