Sorry to throw a second comment at this but some food for thought possibly as I went through this dilemma, granted this was my conversion journey so may differ a lot to yours but some thoughts that crossed my mind.
I find gloss black alloys easier to tie in with further modifications. If you added a pop top and opted for non colour coding, you’d select the gloss black over white from manufacturers, thus tying in nicer with the black wheels.
After market 80% tinted windows. I just like how the windows tie in with the alloy colour but again this is totally personal / biased point.
Updating grilles on the front of the van. I tend to find a lot of gloss after market parts meaning these would also tie in with a gloss black alloy.
I read a lot on the forum of people ‘de-chroming’ their vans and replacing these with personal choice colours or gloss parts. One of the reasons I also went gloss black alloys.
I guess all of the above clearly shows my biased opinion that you should go gloss black haha. But for me personally what sealed the deal was side bars, if I had chosen a silver alloy I would of had to have gone chrome side bars over black and I think they stand out too much against grey and my opinion is a grey van, chrome side bars with silver alloys was just a little too much and found the gloss options to be a nice subtle touch against the van colour.
Good luck with the choice as what ever you pick I’m sure will look amazing and you’ll be over the moon with your selection, just thought I’d throw some points that I thought about when selecting my wheels.