I got a travel backpack, 60L, and feels nice and big, but I just saw one with extra 10L (basically 5cm additional height) for just 10€ more and hmm
part of me tells me that I should go for the bigger one in case I ever need those 10L, but this one is already quite big (and I'm not that strong), and something tells me that "bigger is better" maybe isn't the right mentality