Which is most bitcoin wallet Xapo versus Buxtank?
The first bitcoin wallet was bitcoin core, created by satoshi.
The most used are probably electrum (very good one) and blockchain.com(bad one)
I don't know buxtank and I would stay away.
Xapo is not the best wallet, but it has good reviews.
Bitcoin core is a good wallet with a huge investors base. Even now their are lot of people using of Bitcoin core. I had a account with electrum and experience over it. The wallet is doesn't mean, but you should implemented all the security one. If you had huge bitcoin for example above 1000$, without security will enable the hacking.
