for me best wallets till now for bitcoin bitcoin gold :
mobile :https://coinomi.com/windows :https://electrongold.org/both wallets are safe and do the purpose, just move your bitcoins to other wallet before claiming your bitcoin gold.
so what is the best wallet to use for import private key?
I like my Trezor. BTG claimed without compromising my private keys and it is SPV, so no need to download over 100 GB blockchain.