For the cost difference you might as well go for the 160W.
Keep in mind that neither will fit directly into the ATX connector on the Microserver board, you'll want a 24pin atx extension cable. There are lots of options for where to mount the pico, I was a bit worried about it grounding so put it in a plastic project box. You'll also need to consider a molex splitter and maybe a 4 pin atx extension cable for the Pico 12v barrel input depending on where you want to put it.
Keep in mind that neither will fit directly into the ATX connector on the Microserver board, you'll want a 24pin atx extension cable. There are lots of options for where to mount the pico, I was a bit worried about it grounding so put it in a plastic project box. You'll also need to consider a molex splitter and maybe a 4 pin atx extension cable for the Pico 12v barrel input depending on where you want to put it.