That's a matter of personal preference and how much you want to feel different by having special diamond brand.
Ask yourself how pragmatic you want to be when buying diamonds
I do not care much about diamonds at all or any diamond brand in particular so I will be boring and over analytical
First, I would look at both to see whether I see a difference in cut/appearance and which one I prefer the most.
If I would see a difference and prefer 8*, I'd start thinking about price difference and whether 8* is worth the difference for ME. Assuming both cost the same, 8* should be almost 95% more expensive considering difference in size, color and clarity.
However, I may also not be able to see any difference in color (both are pretty white), clarity (only with a loupe) and size (spread, diameter), then I may not care about difference in these 3Cs and only compare the look of the diamonds and my personal sentiments or desire to possess something that I may (or may not) believe is non-ordinary (brand, artistry, philosophy, religion, etc - whatever else 8* may mean for me - personal things again).
Last but not least thing I would think about is resale value. I don’t have answer for this because I don’t know how easy it would be to sell 8*. Someone else, however, may not care about it at all.
Again, all these speculations is my personal approach and I would use it to any other brand or type of diamonds.
You may care less about money and only care about getting something you (or others) believe is special, then go for 8*.