If your in the US then as far as I know coinbase is the best place to purchase your coins. It's not the best place for trading as it has limited coins that you could trade. Id recommend accounts with the exchanges Bittrex, Poloniex, Kraken and maybe HitBTC (for small trade coins). Or just pick one to keep it simple. Then send your coins from coinbase over to your exchange account. Then set up the API connections on coinigy with your exchanges.