Safer? It depends on how the November fork plays out. It will be safer to use whichever node the other people you want to transact with are using.

btc1 will follow Segwit2x. Bitcoin Core will not.

Currently, 90.9% of the network hashrate is signaling support for Segwit2x (https://coin.dance/blocks). Segwit2x also has the support of Bitpay, Coinbase, and every other major Bitcoin company that has registered an opinion on the matter except for Blockstream. Blockstream, plus a number of smaller companies (Échange de Montréal, Bitbrains, Bitstop) oppose it (https://coin.dance/poli).

Personally, I think Segwit2x will be the dominant chain. The data seem to be in its favor. I could be wrong, though.

The blockchain downloaded by btc1 and Bitcoin Core will be compatible until November. If you want to switch, all you need to do is stop one bitcoind and start the other. After the November fork, though, it will require you to resync your blockchain in order to switch between the two.

veqtrus's code (v17 shares) is incompatible with btc1, and only works with Bitcoin Core. My code will work with either btc1 or Bitcoin Core, though it will give you a warning message if you try to use Core.