Hi Kristie, welcome to Steemit.

First of all, what is your objective here? Are you looking at a long term investment? If so, Coinbase and Kraken are just places to buy, not to store your money. Both are perfectly fine for buying, I tend to use Kraken and it has both Bitcoin and Monero available. Steem is only available on Poloniex, Bittrex and Blocktrades though.