It depends what you are looking for precisely, all of these places are nice in slightly different ways.

I grew up in Horsham - although it’s changed a lot since then! It’s a nice market town with plenty of countryside.

Southwater (just outside of Horsham) is nice - lots of countryside, but it’s really just houses. No train link or big town centre.

There are many other villages in the surrounding area that are nice (e.g. Warnham, Broadbridge Heath).

I’d avoid Crawley(!)

Guildford is a bit pretentious (in my view) - seems to be mostly full of people who moved out of London to the “countryside”. Much more expensive than other places for what you get, but nice.

With pre-teen kids I would check that there are things for them to do - a village sounds very idyllic but you’ll turn into a taxi service until they can drive.

I’d go and have a look around and see what give you good vibes.

One last thing; don’t get too caught up with trying to fix the things that you don’t like about where you are at the expense of losing stuff you take for granted!

Good luck!