I've been using Coinbase for long-term investing, that's where all my bitcoin is right now. However I also wanted to find a site that would allow me to deposit USD into the account so I could buy/sell btc instantly, without the long Coinbase delay.
I'd say that this will never, ever happen on a website. Fiat's chargeback problem will always exist, so the only way around this in the forseeable future is to trade physical cash for bitcoins.
One day though there will be decentralized solutions to this too. They've been theorized but I don't see anyone working on one because it's sure to be instantly pronounced illegal.
Two hacks totalling about 4100 BTC have left Inputs.io unable to pay all user balances. The attacker compromised the hosting account through compromising email accounts (some very old, and without phone numbers attached, so it was easy to reset). The attacker was able to bypass 2FA due to a flaw on the server host side.