I’m a big fan of anthracite coloured alloys - had them on my last two cars. Anthracite or gunmetal hide brake dust and work well with most car colours. The alloys on my current car are Ferric Iron - lighter than anthracite but darker than silver.
From a cleaning / maintenance point of view, I always think that black alloys are similar to a black car; unless just washed, they always look dusty or dirty (road grime or brake dust) and they show swirl marks. The design of the wheels is also ‘lost‘ unless you’re close up to the car.
Given the choice of anthracite/ gunmetal or black, I’d always go for anthracite or gunmetal. The only time I’d choose black is if the choice was between black and diamond cut alloys as I dislike diamond cut alloys with a passion!
Edit; you’ve not said which alloys you have on your car - IMO alloys with wide spokes (e.g. the standard 17” alloys on the Leon FR) don’t look great in dark colours. If you do have the standard 17” alloys on your car, I’d be inclined to go for a darker shade of sliver, or shadow chrome as suggested by
@Leeoncupra.