The best answer here is to test it out. Each Social Media has its limits when it comes to automation so better you try with some proxies and decide which one is the best. Of course, 4g is the best but it comes a bit pricey, but if you are serious about automation and want to do quality work, then this is the best choice. If I would be you, I would just go around in the Market > Proxy and ask for trials and start testing it. Of course, you will churn and burn some accounts but it might give you an idea of what is working and whatnot.