Personally I wouldn't invest in any fork (bitcoin cash, bitcoin gold) just stick with the classic currencies, if bitcoin will go down it'll bring bitcoin cash with it but if bitcoin cash would crash is unlikely to bring bitcoin down, in my opinion.
Well if we look at example with ETH and ETC coins we can see that forked coin got up there, mainly because of devs switching sides but still. I don't know anything about Bitcoin gold but can tell you from my opinion and opinion of others bitcoin cash might still be worth buying. What I mean I'd that OP can devide his investment between these two or simply divide between more coins. Bitcoin cash has some good people who advertise it by attacking real bitcoin since bitcoin is in real need for upgrade transaction taking days to process.
Always cheaper coin can grant you faster gains and losses, bitcoin will or at least should stay in the game because it's the first thing that pops out in majority when it comes to crypto currency.