For gaming, heavy downloading, get ADSL as the data is cheaper and its more stable + Less ping. Speed depends on what line speed is available to you.
If you have good LTE signal where you plan to use it, you should get very quick DL and UL speeds. Vodacom, MTN etc all offer LTE. Another bonus is you can take your LTE with you wherever you go, depending on signal.
Basically it all depends on your internet needs, how you plan to use it.