Don't go with the mentality that the most expensive ESC will "buy" you the best results....
You DO however, need an ESC that gives good throttle and brake "feel".
Different races have different expectations on how to achieve this and what is classed as acceptable.
I know of some racers who are happy with an EZ run esc, yet others prefer something with a better racing heritage to it.
Ask around your local track and see what other guys use. Ask them what makes a good ESC for them. You will get a wide range of answers, go from there