What are some thoughts about the different types of materials used to make yo-yos and some of the different effects added on such as bead blasting?
I prefer 7075 aluminium purely because of how shiny and resonant it is. There’s something about a shiny yoyo that just looks better to me than a normally anodised one.
Case in point, the Onedrop Valor. Still pyramatted so it grinds decently, but with that beautiful shine.
Blasting is handy simply because it grinds better and has less risk of slowing down if you accidentally knock it. Something like the C3 Krown has the best of both worlds IMO with a shiny cup but blasted catch zone. 
I’m actually more partial to 6061. Sure 7075 is more durable and doesn’t ding as easily, but they tend to play a little heavier and I’m ALWAYS smashing my knuckles with them. Probably because they typically have have a stronger spin than 6061.
I greatly prefer my yoyos to have some type of blast. It’s part of of the reason why I got a matte black Draupnir as well as why I sort of hate my Anglam 
dependent on shape for me. i usually want a blasted V or H but a raw like O is nice. V’s and H’s HURT like bagiggleshiz when it smacks your knuckles or even forearms and shins. SO its nice to have some non-friction forming ano to help resolve that issue. But then to types of material 7075 is my favorite cuz its usually with in my weight range or alil higher, which can be problematic at times. but the spin time and weight on the axis is vunderbaugh.XD But most of my throws are 6061 which is nice to do easier flowing tricks. definitely a preference thing for me…babble bbabbababbakaajaad…sorry…type vomit…
There are gobs of different types of media to use for blasting. Different pressures can yield different effects with the medias. As for the material being blasted that to can be manipulated to achieve different depths and surface texture.
It comes down to what you are basically trying to achieve in the end. Better grinding surface vs. the final look of the anodized product.
I prefer my 7075 yoyos to be blasted with baby pickles, pine nuts and pepper corns.