I've tested a lot of those maps before, so I'll share my insights, just as advice since I'm not telling you what to put on your server.
zpo_graveyard = full of bullshit spots, the only reason we kept it is because the map has a button that plays "Thriller"
zpo_iceland = would be a good map if someone could optimize it, it does have videolag because it was poorly optimized
zpo_funhouse = very ridiculous map, if you don't have funnights or something where you just fuck around, there isn't much reason to have it
zps_inca = this map is bad. We had high hopes for it, but theres this nice temple in the middle of a HUUUUUUGGGGEEEEEE open area, like it feels like you walk for a mile just to get to the temple, and then realize zombies spawn there and the humans spend forever running around the wide open field around the thing, and you might as well just make a map of a big grassy field and play in that instead. If someone could shrink down the massive field between the temple and the map walls it might be playable, but in its current state its just funrunnerland.