For context, my IRA contributions are entirely "backdoor Roth" and it's invested in a low expense ratio S&P500-tracking fund. Consider these facts to be non-negotiable: they will be true no matter what we decide below.
What should I take into consideration when choosing between these two situations?
A: Use a broker that offers a 0.02% expense ratio mutual fund (symbol: SWPPX) but does not match my contributions.
B: Use a broker that offers a 0.03% expense ratio ETF (symbol: VOO) but matches my contributions by 3%. If the match ever goes away, I would switch to broker "A" at that point. Note: my own contribution (say $7000/yr) will use money on which income tax was already paid, but the broker's contribution (say $210/yr) will be taxed like any old 1099-INT, so my overall income tax liability increases by say $50 (assuming 24% marginal) but any gains on the whole $7210 would be tax-free.
I'm wondering what's more valuable in the long run: the match or the better expense ratio. And any other considerations, like if the choice between a mutual fund (the best choice for broker A) and an ETF (the only choice for broker B) matters.