For chaos I always go for t3 armor, love how it looks with my appearance items. Lsm I always go for at least t2 armor. For some reason I just hate the look of the marines without any trim. Orks I'll take whatever I can afford, but I prefer t2 because it doesn't cover up my go fasta flame boots like the t3 visual does. Eldar don't get any new flash from armor, so yeah stats for them.
I think stats should be completely separate honestly. The devs are so focused on having visuals for a lot of the stat stuff that it seems like it's hurting the cosmetics. A lot of the armors for the marine factions go against lore and in some cases just override cosmetics that people have paid actual money for. The same thing goes for Veterans, they all look awesome for the most part and have the massive dorrito above their head. Just make the vet cosmetics a rank 6 unlock or something for base classes.
