I had a bad experience years ago with a bag from a brand that seemed solid, but after less than a year the strap started coming apart at the seams. Since then, I always try to invest a bit more upfront rather than throw money away on something that disappoints me right off the bat. What I've noticed is that serious European brands really do hold up, especially if you pay attention to the details: the stitching needs to be tight and even, the leather needs to have the right thickness (not tissue-paper thin), and the hardware (buckles, rings) needs to be sturdy and properly secured.
Italian ones like Gabs or Leather Factory are genuinely good, but honestly if you want something that lasts with minimal upkeep, also look at lesser-known brands you'd find in certain independent European shops. A lot of Spanish and Portuguese artisans make genuine leather bags at reasonable prices - they don't cost as much as the big names but the quality is surprisingly good. The trick is not to expect a decent leather strap to cost like 40 euros: around 100-150 euros you start finding serious stuff that'll last you years.
When you buy, check that the leather is natural (not synthetic passed off as leather) by touching it and smelling it, look closely at the stitching if you can, and pick a neutral color that goes with everything. Dark shades (black, dark brown) hide scratches and the natural wear of leather better.