Poodles, despite their cutesy-wutesy curly-wooly appearance, is actually still a highly instinctive hunting dogs that used to hunt other animals. They tend to chase and bite on small things that run away or across them, often going for the throat, and hence, their (not-too-deserved) reputation of being the "child killer" breed of dogs.
You need the breeders in Medieval times to breed poodle solely for their wooly appearance, and perhaps, downsizing their size (but even small poodles could be still quite strong in their hunting instinct, heck, the smaller Italian poodles are very effective rat-killer).
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And about the Big-Ugly-Sadie that is The Pit Bulls, they are originated from Cart-pulling Molloser Drafting Dogs that crossbred with Bulldogs, rumored to get the big, vicious dogs during the 18th century, but they turned out to be sweet, gentle giants that, while still exhibiting a high pain tolerance, prefers to bond with their owners' family as a sweet, almost docile pet that absolutely loyal to them.
Being used to pull meat carts (and thus being streotypical butcher's dogs during 19th century and early 20th century), Pit Bulls breeding were self-selecting for calm, obedient animals that wont even eat unless given permission by their owners. This could result in a range of problem from overfeeding (as they will eat anything their owner gave), up to malnutrition (since again, they won't eat unless given permission or signs, as they were disciplined to not nibble at meat they carry), and for most pitbulls who live with children, they tend to be overweight (and prone to get poisoned by chocolate/grapes, always teach your kids to not giving them those).
Yes, they have ugly face, but well, their sweet temperament makes up for it