Which has more slippage, FX or Stocks?

The general answer: Stocks. Your specific scenario: It depends. Your other posts mention OTC Pocket Option and Binary Options aren't FX or Stocks (not to be a dick early in the morning, but it's in the name. Options). You also failed to mention things like when you are scalping, are you doing this during major news releases?

FX, for the average retail trader trading major pairs, won't experience much if any slippage. The market makers are ready to take any order (within reason) at any price. Stocks on the other hand can be wildly different, and in the realm of options you can, pretty frequently, run into things like partial and no fills. Partial and no fills are possible with stocks, and even FX, but it's rare assuming you're talking about stocks like American Express. The story changes if you're trading a low volume penny stock; and again, Binary Options aren't FX or Stocks. While you can trade FX and Stocks, they are an options contract. Buying Microsoft stock and buying Microsoft options are two completely different ball games.