Should I buy into FXAIX or VOO?

Hey! I am a beginner investor that younger and just started my account on fidelity a month ago. I have been putting around $400 a month in FXAIX, but was wondering if I should switch to VOO instead. I have heard that etfs are more tax efficient and I don’t want taxes coming back to bite me later on.

What should I do? Is it worth selling my $400 from last month to buy into VOO along with this months earnings?

Edit: this is a taxable account, not a retirement account.