Can't say I'm attracted to futa or loli, so not a clue on there. I did ask a bunch of people(48, online) at one time about futa and I may as well post the results here. As a note, this was asked in multiple futa groups online, so the sample may be biased
2016, 06, 24
48 total surveyed
Likes: 35
1 Hates men, likes dicks
1 Is a woman, wants to have a dick
6 Prefers the female body over the male
"sex without dicks is like cake without cream. but "masculinity" is not my flavour"
12 "They have all the fun bits"
2 "It's like a woman with a strap-on"
5 Bisexual doesn't want to choose
2 Superior evolution of humanity's future
1 Breaking society's view on sex
1 Can hold on to the dick as a handle while fucking
1 "I love dicks on everything"
2 "I just like it more"
1 "Beautiful art of the mixing of masculine and feminine, unified both sexes"(Insert 5 paragraphs)
Dislikes: 3
1 Doesn't want to tell more
1 "Cop-out", like wanting a cock but not willing to commit to a man. Men with tits.
1 Has his immersion broken by it
Neutral: 10
3 Not into it, but not disgusted
2 Completely neutral, gives no shits
1 Doesn't enjoy them, can't feel immersed with dongs the size of trucks
4 Uninteligible
Depending on how bored I am, I may try another survey sometime to see how things changed, if at all
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As for furry, generally I'd go with the more human side of things so I guess I'd get things closer to monstergirls etc, but in general some animal-like features and traits are attractive. Cat ears, mannerisms, and tail would make for a simple neko. Now just add some more fur and you have something like Felicia from Darkstalkers. But then why stop there? You may as well put on more fur and more animal features and go full on anthropomorphic animals. Imagine the good parts of the animal with a human or close enough to human intelligence to minimize or outright remove the bad.
Thus;
Dog furry:
Playful like a dog
Enjoys being petted and/or touched like a dog
Loyal like a dog
Smart enough to not chase cars or random cats, squirrels, etc
Smart enough to deal with fleas and keep themselves clean using hair care products
Smart enough to not roll around in the mud or take a leak on the furniture
A best of both worlds sort of thing, essentially. Though the fact there's a lot of
different things one can do with it, such as genitalia, mating habits, and so on will also appeal to the more adventurous. In general, it's just the application of desirable traits of animal to a character, or the outward display of such desirable things