open wifi and tor would be the easiest. tons of places have free open wifi at this point. it's even easier in a lot of countries outside the US where you can pickup a SIM card for $1, but it won't be the fastest connection.
internet cafe is questionable if they have cameras either in the shop or along the street outside, but that would have to be police or other gov agency looking for you to go to all that trouble - though i could see 4chan going through the trouble.
proxy servers can have logs so not to be trusted, and if you own the server that wouldn't be anonymous at all (unless you purchased the server or proxy access with a stolen/fake CC, but then you wouldn't be using a connection that could be traced back to you anyway so you're back to open wifi, tor, or anonymous SIM anyway which makes the proxy redundant).