I always preferred Vanguard and have my Roth there, but my larger workplace accounts are at Fidelity.
Ten years ago, I addressed this by:
* setting up BrokerageLink self-directed brokerage window at Fidelity
* directing bi-weekly contributions to Fidelity (then "Spartan") index funds, which did not have as favorable ER as Vanguard's
* for asset classes where I really preferred Vanguard's offering, once a year I'd take everything over Fidelity's minimum fund balance and send it to the equivalent Vanguard ETF, eating the $7 commission just once per asset class per year
* Fidelity offered iShares ETFs commission-free, so I replaced many ETFs with those
* Fidelity started offering some more competitive index funds, so I made these my defaults, of course with no commissions
* Fidelity got rid of the fund minimums, so no need to worry about them anymore
* My only Vanguard ETF holdout as of recent years was VWO Emerging Mkts ETF, and not because I didn't like Fidelity's offering, but rather because I didn't think it was worth even the then $5 commission to switch all my emerging markets into one fund.
Now, I guess I have no excuse. I can consolidate that last ETF into one fund for free. Being cheap and lazy can work in your favor!