Bitcoin Gold is basically just a change of the mining algorithm from SHA256 to Equihash. It is intended to return power to users mining with GPU instead of the ASIC powered centralised mining. I am not convinced it will have significant traction though it might get a lot of support from small players.
SegWit2x is basically an increase of the block size from 1MB to 2MB which is part of the New York (Peace) Agreement that was struck months ago, even before the last fork of Bitcoin Cash. That agreement was to implement segwit and then increase the block size and it had over 90% support from miners. Problem is the Bitcoin Core development team do not support the blocksize increase and only wanted the segwit activation so it is likely to cause a coin split also.
Bitcoin Gold IMHO will just be seen as more free coins that can be dumped and pose no real threat to BTC. But SegWit2x may actually have enough support from miners and big players that it could genuinely split the market cap of BTC. Time will tell. There is no specific date for SegWit2x (other than a vague notion of it happening in November) but Bitcoin Gold I believe is happening on Oct 25.