Horsham is nice, albeit being developed. I am currently purchasing in the rough local area, slightly lower budget than yours.
My criteria in priority order:
I drive to work in Sussex but girlfriend works in London 5 days a week so wanted somewhere she could walk to the train if needs be.
We're young so want a larger town with a bit more going on
Min 2 bedrooms
Min 2 full bathrooms
Parking for 2 cars
Minimal work needed
Potential to extend or convert loft
Potential to fit solar panels
Potential to charge electric car
Areas I looked at:
Horsham - I like it, at my budget I was struggling to get somewhere with parking for two cars anywhere near the station. If you don't mind being further out and driving to the station/long walk to the town centre then there are better value houses
Haywards Heath - fast train in to London, reasonable size town, better chance of getting housing near the station
Hassocks - small but nice village, on the same line as Haywards Heath, 10 minutes further away, fast-ish trains to London. Concluded a little too small for us.
East Grinstead - Reasonably nice town, very easy to get housing near the station, overall found houses of better value than Horsham. Slower train to London.
Reigate - Nice town, can get housing near the station but definitely the most expensive of the above
Redhill - Girlfriend doesn't like it, but looks like you can get plenty of housing close to stations with reasonable value.
If you think you can drive to the station and pay for parking then it opens up a lot of options for towns and villages. Three Bridges is a big commuter station with a large car park and fast trains, so for one day a week you could consider many towns nearby.
Jet noise not really a problem in Horsham, although you tend to find you get used to it very quickly anyway.