I think the thing is that quality and durability are two very separate issues and that many
very high quality bags won't be overly durable, due to the delicate nature of the materials used in their construction.
If your main concern really is durability, rather than aesthetic appeal, then perhaps a
Prada nylon bag would be a good choice (not that they're ugly!)? Members on here have Prada nylon bags that they've been using consistently since they first came out in the '90s and they're still going strong!
Obviously, if you want long-term durability and for the bag to still look as new as possible after lots of heavy wear, avoid very delicate materials like very soft leathers and silks and go for black, or other dark colours (e.g. brown, navy or burgundy), with similarly dark (rather than contrasting) thread.
Typically, I think the thicker and firmer the leather the more hard wearing it tends to be - although this isn't a hard and fast rule, as very hard leathers can be more prone to scratching, in my experience and some very soft leathers, like those used by BV, almost seem to 'heal' themselves when damaged (bizarre, I know - makes you wonder if they use unborn animal skin? :s
).
So the compromise would probably be a thick, firmish, but still flexible, leather.
This may not be that easy to find, though, as I think most designer brands seem to use either very/quite soft, or very hard, leathers most of the time.
If you do want leather, rather than a durable fabric, bear in mind that all leather is a perishable commodity that has to be looked after, to a certain extent and that dirt/grease/salt from hands, heavy rain and impact from use etc. will all affect it over time, however relatively durable a leather it may be.
In terms of construction, most high end designer bags are going to be well made enough to be durable, assuming they're made from durable materials; however, some bags/brands are known to be susceptible to 'quirks'.
Chloe (much as I love Chloe!) is one of those brands, for example...
Which brings me to my next point, which is innovation - the newer a design is and the more new and innovative designs a brand tends to puts out, the more likely it is that there will be 'issues', as the first customers are, effectively, the guinea pigs for the new design. This is pretty much to be expected, though, as fashion companies, obviously, don't have years to test new designs for possible faults before releasing them.
However, if you do want the first release of an innovative design and anything does go wrong (with normal use [which is, basically, using the bag as a bag!]) within the first year, or so (and most of these faults normally become apparent pretty quickly), it should always be possible to get an exchange or a refund.
My final thought would be simplicity. If you want a better chance of durability, go for a simple design in an ergonomic, easy-to-use shape (for ease of use [which should decrease the risk of wear/damage]), without lots of bells and whistles; as if you do, there is, obviously, less to go wrong.