I agree with people who said usually Wyldside, but it depends on the board state.
Early game, Wyldside is almost always the best choice, as it feeds Faust, gives the runner the support and economy cards he needs and drastically speeds up the milling.
If other copies of Wyldside/Pawnshop are in the bin, it can change the calculation.
If the runner is poor, pawnshop might be the better bet, because now you've temporarily shut down the economy engine, he needs to stop and spend money to clear the tag, then find another pawnshop to restart the engine.
Sometimes if the runner is poor and I have my choice of two resources to trash, I'll take out chronotype and pawnshop and leave Wyldside alone, with the rationale being if he doesn't have levy, every card he discards because he can't play it is one less card I'm being milled -- and a turn closer to him running out of gas. He'll surely be floundering for a few turns with one less click and no cash coming in. Great spot to find a scoring window or two.