I would agree with the CZ PCR but in my area CZ's are not that big of a savings over Glocks.
I would still go with a used Glock 19 over the PCR but the PCR is the closest gun to what your attempting to accomplish. Most of the other guns mentioned here are heavier or bigger or equal in cost. And the Sigma's trade off is a very mediocre trigger. To me the Sigma is overpriced at $250 when I can find used Glocks around $300-350.
Also Glock mags can, generally, still be found cheaper and more plentiful than most other guns mags.