Im living in Buenos Aires currently and I must it is a dope city to skate. You have great public transportation (subte, buses)that can take you pretty much anywhere in the city pretty quick. There are a ton of spots especially if you actually go out and skate around to find shit. There are a lot of skateparks that are public plazas so they are open 24/7. Skating is not sketchy at all, you just have to be careful and look around where you are especially if you have camera equipment. The spot Id recommend going to is Plaza Houssay which used to be the meet up spot and now has a skatepark. You can meet up there warm up and then hit the streets. There is also a sort of market on saturdays where skaters sell stuff like boards, shoes, etc all for much cheaper than the local stores.