Tough poll for me. I've only had oral sex (receiving) with an animal. It was defiantly better than any I ever received from a human (something about that rough dog tongue). But I've never penetrated, so technically I've never had sex with an animal. If I had to guess, I think I'd like sex with an animal better. I'l not lacking in the length department and sex with human females can be frustrating when you can't go deep. So I have to go for a specific type of women, either fat of tall. Otherwise it just hurts (which I'm into as well but not everyone else is). I'd imagine that with the right species/breed, I could go as hard or as deep as I liked and it wouldn't be an issue. I dont know, but would love to find out.
You should try dating a latina, there are small ladies (150cm) that can easily Take 20 to 25cm of Dick, ir course not all ladies can, but many do. Maybe there are more people from latin america that share the same experience.