My family own and manage a game store, and we have been into MTG and many other card games since their inception. We like KMCs the best all around, though some prefer Dragon Shields' color selection and price.
I believe Ultra-Pro sleeves have been gradually declining in quality. I have seen too many packs with QC issues (incorrect cuts or gluing, etc). They are the smoothest to shuffle, but show wear the first time they're shuffled, especially non-Pro-Mattes. For a Commander deck I invariably choose Dragon Shields (100ct). For a 60-card deck, it's always KMCs (Only available in 80ct). Most of our customers (especially the more experienced) miss the old days of Ultra-Pro, and end up doing as we do.
BCWs are excellent sleeves when you can find them. Plainer and less color selection, but very affordable and durable. I like them better than Dragon Shields but not as good as KMCs. They're the best 'inexpensive' sleeves by miles.
This all depends on the pricing of your shop, of course.