The criteria in the OP were
' I have dogs so good walks/green space is important (brilliant in Edinburgh) I like beautiful architecture, big open skies, and easy access to countryside. Plus city comforts - bars, cinemas etc. I’m also quite active so a decent climbing wall, running club etc would be good. '
Dog walking and green space, very good in and around both Preston and Lancaster. (Manchester, the centre anyway, is almost entirely devoid of green. )
Beautiful architecture - no, not anywhere in Lancashire tbh. Both cities have some ok parts.
Big open skies - you can have any sort of sky you want in this area. Hills, coastal plain - on a clear day, climb a hill and the sweep round Morecambe bay, towards the lakes and then the dales.
City comforts - I don't know about bars. There are cinemas, Lancaster has a good (and not hideously expensive) theatre.
Climbing and running certainly available.
We moved to the area for DHs work - for many people that really is the most important thing, what you do 8 hours 5 days a week, salary, career progression. Now we're here, and at a point In our work where we could move anywhere with decent broadband, we've no particular desire to move. Everywhere has pros and cons, we've found more of the pros over the years.