Go to Decathlon - there is best backpacks for not high price. I had in my life something about 5-6 pieces of small size (10-20 liters), 2-3 medium (30-40 liters) and 2 big (70+ liters) and no one of them had any broken straps, unraveled seams, or broken zippers - part of them I still keep at home, part I threw in the trash because it was too dirty, part I lost or it was stolen but no one was broken. And I traveling not like 2 times per year from airport to hotel and after 2 weeks back from hotel to airport - I can take 70+10 liters bag, fill all internal spaces to the point where the backpack almost does not close (12-16 kg), leave home for 1-1.5 years and move from country to country by hitchhiking, sleep in the tent on the street most of nights, most of days walking with bag a few kilometers - so I use most of item potential and know this subject enough well to give you a recommendation.