There are so many different bags and brands available that you should specify more constraints if you want more personalized recommendations. Vegan is not too hard to satisfy - most luggage that's vegan won't necessarily mention it, you just have to look in the description for animal products to avoid (leather / suede mostly).

For me personally, my main carry is a Tom Bihn Techonaut 30 - it's big enough to carry 5+ days of clothing and my laptop and other gear without needing another bag, but lightweight enough that when I need more space, I am happy to carry it as just a small backpack alongside my Travelpro Maxlite 5.

I also like the /r/onebag subreddit.