Obvious preference comments aside, I have one of these case colors so I can talk about it at least.
Mine is a CTRL High-profile in their bronze color:
Here it is with some grey keycaps, GMK Nines. It’s a subtle case color but definitely warmer than a neutral grey. Here it is with the keycaps I settled on for it, DCX Latte:
Personally, I love the cover, but I do think it’s a little challenging to find something that really jives with it - I tried three different brown sets before settling on that one. I also thought it looked pretty good with HSA BoB, but it clashed with some others. I don’t think the lilac one will be too different; it will probably look great with some purple sets while clashing with others, so I say pick the one that you think you’re more likely to have or want to buy a set that jives with it.