PayPal and Skrill are reversible payments so escrow is useless when paying via either of these methods. Escrow cannot protect when paying with PayPal or Skrill. PayPal is reversible up to 180 days.
Western Union and MoneyGram are OK if they are done at a physical branch and not online. Always collect the money first before instructing escrow to release the coins. Do not simply rely on positive online verification of the MTCN or reference number.
Of course, also wire transfer i am ok with. i offering this possibility because i saw many users asking for skrill and paypal