Sorry, but "best" is such a massively ambiguous term..... it makes the question almost meaningless. The only information provided is that it be "less than $500". Does that mean $500, out the door.....or $500 before tax.....???
What do you mean by "best" ? Most reliable ? Most accurate ? Most user friendly ergonomics ? Easiest to maintain ? Greatest parts availability ? Relative expense of parts and magazines, etc. ? Hammer or striker fired ? Etc., etc., etc.
These are all questions important to consider.....and not the only ones. In the end, it comes down to personnal preference anyway. There is NO such thing as one "best" model.....only the one that might be "best" for you.
So, sorry, but in the absence of further coherent information to qualify what you are looking for, I decline to provide any suggestion.