I was going to supply stoats for this reason, but I see they’ve been mentioned already.
As for pack predators: what about dolphins? 
You can tame cheetahs, kinda. And they’re kinda like half cats, half dogs already.
Also, hunting falcons.
Well, more cat than dog, but yes. I love cheetahs, but they are felids and thus toast, per the OP: Cheetah - Wikipedia
You are forgetting about the Cheetos cheetah. I mean, if Cheetos can’t kill it, nothing can!
But there’s only Chester the Cheetos Cheetah. What are we going to do, clone him? 
Definitely ferrets.
We have two aging cats and a ferret. As the cats die off, we’ll get more ferrets.
A ferret will poop in a litter box like a cat and can be broken to a leash as easily as a dog can.
And,guys, ferrets are chick magnets! Any time we take our ferret out in public, women flock to him. The ones with cameras want to have their pictures taken with him.
My wife kids me that she’ll never let me walk the “furt” without her. In reply I always quip that if we ever get divorced, “Take everything but the ferret.”
I vote for guinea pigs. They certainly have personalities, they’re cuddly, cute as all get out, and not much trouble. If they could clean their own cage and do the dishes, I’d have two dozen at least. As it is, I only have two.
That’s a HUGE “if.” We have two, as well, and all they do is eat, poop and sleep. Mostly poop. My young sons have pretty much lost interest in them, and I can’t say I blame them.
As much as I would miss my cats, I have to say that horses are more intelligent and personable than people give them credit for.
Heck, a miniature donkey is probably just as smart as a Border Collie, although it prefers to put its wisdom to different uses. 
http://arceneauxfarms.net/pb/wp_5692cd2d/images/img1161845c432dcb8ada.JPG
The only problem with equids is that they have hard bits on the end of their legs. Well-trained ones are a delight, but even a miniature horse, if spoiled and not given boundaries, can be dangerous, and donkeys are even more likely to take advantage (at worst, dragging you around, rearing or wheeling and kicking if they take serious objection to something) of a person who is not serious about training.
Elendil’s Heir, I had no idea chinchillas were so cute!
A local animal wrangler we know brings critters to nature center events, library gatherings, kids’ parties, etc., and usually brings along a chinchilla. They are excrutiatingly adorable and soft beyond belief. Now I want one!
OOOh!! OOOooooh! I wanna meerkat!!!
Who doesn’t want a Monkey Butler?
Um… anyone who read about the chimp nearly chewing the face off that lady?