Vanguard. Website works well enough. Rarely find a need to use the Android app - I use Mint primarily to keep an eye on my accounts, and Google Now for timely updates of certain stocks/funds.
My stocks are predominantly in Fidelity because I have their 2%-back-on-everything AMEX, which rolls into my Fidelity Brokerage account. $7.95 trades which I think is pretty standard for mega-bank retail trades without trade volume or account balance discounts.
My only other interaction with them is when they send me new cards to activate, like if my card is going to expire or they want to issue me a new number. Activation is all automated and takes 2 minutes.
Fidelity brokerage I think is a separate service organization, and have had no problems with them either about account questions.