RockAuto has been my go-to for years, from my 90s Honda to my current 04 Impreza wagon. Prices are solid.
Be careful with shipping costs, some sites lure you in with cheap part prices but charge a lot for shipping. Always compare the final price before ordering.
If you’re looking for performance parts, I recommend Subimods. Their customer support is great, and they have a solid rewards program. For OEM stuff, I usually just go through a dealer.