Depends what you mean by best…..ie. biggest, poshest etc….I live near the village of cartmel in Cumbria, and Cartmel has a lovely little race course which has meetings about 5 times a year including what they call a BBQ race in July….a very friendly small local course, just outside the village, the village has about four lovely pubs as well,…..it is in the Lake District, so plently of places to stay.

aintree, biggest and best.

For scenery, Kelso.

i like ascot, coz the australian bred and trained horses always win your sprint races!
miss andretti.
magnus.
takeover target.( and yes he’s coming back again this year to win your races and take your prizemoney)
choisir.

Cheltenham in march by far and away beat any other racecourse

and as for why just give it a try for a few days and stay over

For me its Newmarket in Suffolk. Its only 50 miles from where I live and it takes me 1hour 10 minutes to get there all across country.
Not only does it host some of the top races on the racing calendar i.e. the Cambridgeshire, Ceaserwitch, 2,000 and 1,000 guineas and of course Champions Day, but it also has great evening fixtures during the Summer.
For example this summer they have Bryan Adams playing after racing (SOLD OUT), Girls Aloud, Madness and Jools Holland on other Newmarket Nights as they are called and all for the price of an entry ticket.
Forget Ladies Day at Royal Ascot (been there done that and didn’t think much of it) too much posing, champagne and jugs of sangria, gets in the way of racing action which was very difficult to get anywhere near!!!
Yes it has to be Newmarket. for me, the best in the UK.

Depends what kind of racing and the atmosphere.

Big racecourse over jumps (national hunt)- Cheltenham, Aintree
Big racecourse flat- Epsom
Smaller racecourses- look into point to pointing, nice atmosphere and good for picnics etc.

It also depends how far you want to travel and each racecourse has different facilities.