If you are just looking to allocate to some ETFs by Vanguard, there's really no argument left that you need any of these tools. All you are going to do is by SPY or some other ETF and sit on it. Robinhood is very easy for that.
Oh, I've seen those. They're a limited selection of ETFs/Mutual Funds though. I thought you were referring to brokers who had unlimited free ETF trading.
Merrill Edge if you have sufficiently high account balance (>$50k) allows 30 free ETF and stock trades per month. There are nice credit card bonuses with BOA CCs, too.
Most of the big brokers offer commission free trades on ETF's and mutual funds.