Kraken is the most appropriate for US folks. If you can pass the KYC, there are exchanges outside of the US you can buy xtz using bitcoin (i.e. Huboi Global hbg.com). Please don't buy from hitbtc, it's a known scam exchange and you may never get your coins, but again, only buy in $2-300 lots and withdraw immediately. Tezos has an Android wallet called CorTez built by the Tezos core-developers, but not sure if that supports delegating function. Coinbase announced a month ago they will offer XTZ as part of their Staked offering product, we suspect that it will be offered on the Coinbase exchange, as well, but no guarantees. If it does get offered on the Coinbase exchange, it could very well shoot up in price. https://blog.coinbase.com/coinbase-...os-makerdao-governance-to-follow-68f7bc51bc53
Always a caveat comes with any investment advice is to dyor or do your own dd. Anything can be understood if one makes the appropriate effort.