You can do either......assuming you tell us mirror size

And what "is same size vanity? One sink as now or two?

You are keeping this mirror? Amid what else in the bath? Floor , vanity finish etc? It's a 5 x 8 bath with a tub? and linen closet?

More context , more pictures , more info with your query begets you more help

Pairing a 60-inch vanity with a single 40-inch wide mirror leaves about 10 inches on each side for sconces, creating a balanced focal point. For optimal lighting and a clean design, install sconces 36 to 40 inches apart (center-to-center) at eye level, roughly 65 inches above the floor

The vanity is currently a 60 inch vanity with a one inch spacer from the wall on left side. The new vanity will be the same size.

We will have one sink.

We are not keeping the current mirror.

I really am just trying to decide if it will seem too cluttered or squished if I do scones instead of overhead vanity lighting,

Thank you

It won't be too cramped if you select the best sized mirror.

You can also consider having the sconces mounted through the mirror and therefore getting two times the amount of light for the room.

Sconces win hands down, so make room for them, however. Down light from above cast harsh shadows (racoon eyes), while sconces provide beautiful, even illumination.