slow internet vs good modem will it boost my speed enough for xbox one online gaming?

[Jesse]

I have messed around with wifi for years because I could never get ADSL2+ installed in my home for some reason anyway, I recently discovered an old copper telephone line, neither telstra or optus could provide internet but Dodo could and they also told me that optus owned the line into my house wich wasnt a problen for them but It made me wonder why optus couldnt give me internet with their own lines? Back to the point, dodo sold me home broadband UNLIMITED metro for $59.99 a month and I am to provide my own modem or router im not sure wich one, but I see really expensive ones saying will improve connection speeds and so forth but my question Is will it actually like ive been told Im most likely to have a "slower" connec but not "slow" full stop, and I really am sick of having my xbox as an $800 dollar dvd player, so anyone know how and what I need to buy to make sure I can fucking play online?!