Have you tried binance? I personally recommend it. 100% uptime unless there is maintenance for which you will be informed beforehand. Kraken's limit orders don't work for jackshit and their site is mostly down. Since you use Coinbase, it means you primarily work with btc, eth and litecoin and BCH but check binance out. It's best for other altcoins. Kraken is only good because Mt.Gox is paying your coins back there. Otherwise it's of no use.