My first suggestion would be to investigate the local racing scene to see whether there are any one-design classes that are popular within your price range. I spent a lot of time racing one design this summer, (J-22''s, Cal 25''s and few J-105 races). In my book, if there''s a healthy fleet, there is no better racing than one design racing.
In terms of budget, almost any race boat that you can buy for less than $10K is likely to need some new sails to be competitive so budget a sail replacement program over the next few years.
Depending on the boat, most pocket racers take at least 3 people to race with four or more being required for 24 and 25 footers under spinacker. I would scratch the Ranger 22 from your list unless there is a one design fleet. These were designed around the IOR-2 rule and are very hard boats to consistently sail to their rating. The Santana 20''s share a similar problem with the Ranger 22 but are fine in an area where you can race them one-design.
In a general sense I would try to find boats designed around the MORC rule as the MORC tends to produce more well rounded designs.
As someone has mentioned, J-24''s are very plentiful. I personally hate sailing J-24''s but they are good race boats that hold their value and are easy to find used.
If you are going to race PHRF then I second the recommendation of a Wavelength 24. These are really wonderful little boats to sail, but I am not sure that you can find one within your budget.
Some other options:
These are real sleepers. They are fast boats that have a reasonably nice interior. They are quite easy to sail to thier rating in most regions. They are not all that well built and so most that have been raced hard are beefed up around the main bulkhead. maststep and some around the keel area.
Farr 727 (Northstar 727)
These are really neat little boats with a gift rating in most areas. They were quite an advanced design when the first showed up in the early 1970''s. Like the J-24 and Kirby 25, they take a little time and skill to figure out but are great platforms to highly develop skills and are highly capable of winning races.
These are pretty cramped down below but are a lot of fun to sail and are spectacular light air boats. Raced one this summer and it was the most fun that I have had racing in years.
Think of these as slightly a slightly more sophisticated Canadian J-24''s with a better deck layout and more durable construction. I owned one for years and really liked the boat.
These Shad Turner designed Fractional riggers are reasonably competitive and should be a good PHRF boat.
I''m out of time here. More later.