For years I bought leather boots by how they looked stood still in a shop, and that is precisely the wrong way to judge them. The pair that mattered turned out to be the ones I almost walked out without trying, because the leather felt a bit stiff at the counter and softened properly within a fortnight of actual wear. What put me right was a disastrous pair that looked wonderful under the shop lighting and cut into my ankle on every single walk for a whole winter, because nobody had told me stiff at the counter rarely means stiff for long, and soft at the counter can mean it was never going to hold its shape at all.
Before you commit, bend the boot in your hands the way you would a book, and look at where the sole meets the upper, because a hairline gap there now is a soaked sock in November. Check the lining goes all the way down into the toe rather than stopping halfway, press your thumb into the heel to see if there's a proper stiffener or just lining pretending to be one, and have a good look at the stitching round the welt, since uneven or sparse stitching there is usually the first thing to give. The zip matters more than people admit when they're buying boots, a cheap one will stick by the second winter, so work it a few times before you decide. What separates the good pair from the disappointing one is mostly in things you can't see from across a shop floor, a full grain leather that will develop a bit of character rather than a corrected grain that cracks along the crease line, a sole that's stitched or at least properly bonded rather than glued and hoping, and hardware that doesn't go tinny looking after one wet week. A boot that's been finished well will take polish evenly, a disappointing one will drink it in patches and never look right again.
I'll say plainly where leather boots are the wrong choice. If you need something for genuinely filthy conditions, deep mud, proper hill walking, they're not it, and you'll end up disappointed comparing them to a boot built for that job. They're also not forgiving of being left damp in a bag or a boot room, leather punishes that more than most fabrics do, and if you can't commit to letting them dry properly and feeding them cream now and then, you'll get two winters out of them instead of ten.
Next time you're trying a pair on, check the heel to toe flex and the welt stitching before you even look at the price tag.