Best mobile in Poland?

[Motel75]

The initial credit on SIMs relative to their cost is nearly irrelevant as a deciding factor, considering that many of them are available for 5 zloty or so. (Please use Polish currency when discussing Polish products, it's easier to see what you're talking about.) You will probably want a SIM that you can buy right away at the airport, and neither of the ones you mentioned meets this criterion (one is Internet-only and the other is only sold at Carrefour supermarkets).

I generally recommend Heyah, as it has cheap data, the now-standard 29 grosz per minute national rate, and calls to the rest of the EU cost 59 grosz. Calls to the US are not especially cheap, at 2.18 per minute, but better than some other offers.

If you're going to be coming to Poland every year or so, you might consider Play Fresh, because you can keep it active cheaply (even a 5 zloty topup extends account validity by a year).

As Przemolog says, what is the "best" for you? Minor differences in initial credit and national call rate aren't the only factors, especially for a short-term overseas visitor.