I can't compare like with like, but:
1. Swarovski.
2. Zeiss, but my only experience is with the Conquest 8x32 HD. Which is an excellent bin.
3. Leica, but only on the basis on the 8x20 Ultravid (though I have the Monovid, which is astonishingly good and, I find, more usable than the Ultravid). On the other hand, that 8x20 is often said to be the best of its spec, and I can believe it.
Only returned one instrument to the makers (suppliers, whatever) and that was to Swaro for my old Habicht 10x40s. A minuscule amount of slack developed on the focus wheel after a year, but you want perfection. Though I'd bought them elsewhere, took them to In Focus (retailers) expecting them to be adjusted by the shop. Went to collect them and found they'd been sent to Austria and arrived back. Focusing now perfect, no charge by Swaro or shop. In the box was a work note by Swaro saying (in German) "Complaint!". Evidently they were surprised to be asked to fix the "problem", but like I say, you want perfection. They served me well for 25 years and have gone to a relative.
Swaro's only fault (if people consider it one) is a bit of stiction. I hardly notice it now, and in fact found a way to improve it. A couple of years ago I thought my 10x42 SVs had developed a horrific problem and posted on BF about it. The focus wheel only moved a small amount each way and made a grating noise. I'd forgotten that the night before, I'd knocked the bins off a coffee table on to the carpet, in to a small gap between table and wall. I'd retrieved them by lifting them up by the focus wheel (???!!) thereby pulling out the dioptre adjustment, and next day trying to use them normally (sigh). But after this mishap, stiction was all but eliminated. So now, a couple of times a year, I briskly turn the dioptre to its full extent each way, and stiction is reduced so that it's scarcely noticeable. No idea why this works, but for me it does.
Excuse the lengthy answer to a simple question. Probably won't return here until tomorrow. Eyes getting tired from screen and playing with a new optic which arrived today, Canon 18x50 IS. Will report on that in due course in the appropriate place...