Reddit reviews Moto Bearings Moto Deluxe Bearings - Moto Derby Skate Bearings - 8mm

Easiest upgrades are the Bones Reds Bearings if you're still using stock Kwik ABEC's (if you've never changed your bearings, you probably are).

For roughly the same price, the Moto Deluxe Bearings are gaining popularity as a better built bearing. I've been using them for a few months. They're very good, but recently some of them are making a very loud clicking noise when I roll, even after cleaning and re-greasing them. Due to that, I'm not 100% on recommending them as of yet, but they're definitely an option to explore if you want to look for more input.