I was wondering if there are any guides or input on which dogs are the easiest to mate with (male or female). Obviously larger breeds are better than say a chihuahua lol but I was wondering which breeds people have experienced working well. I would imagine there are some larger breeds that might also be too aggressive for a beginner.
Furthermore are any that are particularly horny compared to others? Or is it all on a dog by dog basis?
Firstly, and most importantly, never choose a dog based on how good you think they'll be with mating!
Breeds don't change a dog's personality much, and choosing one for how good you perceive they'll be is a mistake. There are too many variables that go into how good of a fit a canine will be for a beginner to make a good argument one way or another. My first was a black lab, and despite comments I've seen that they're a good beginner breed, mine had a very large knot for his size. So much so that I couldn't handle being tied to him. He was also so hyper that he was very hard to control after mounting. Normally I like to give up control to the dog, but everyone has their limits and I still have the scars to show for it. I've also had a 6 year old husky that was the most docile, lazy, and huggable teddy bear most of the time, but as soon as I got naked and into position for him his whole attitude shifted and he became the most aggressive partner I've ever had.
This goes back to how people don't train dogs to mate with us, it's instinctual for them. Instead, the dogs train us, and we adjust. I normally choose a dog based on how we interact at our first meeting, the dog will emulate his or her person more than you realize, which is why now I prefer raising puppies. Their temperament and attitude will very closely meld with your own without you even realizing it, and it's a bond that lasts a lifetime. It won't matter if they're too big or too small for you at first, because you'll adjust, and you'll bond.
Obviously, you'll want a size that is compatible with you though, you can't really adjust to a Chihuahua or a Corgi, but you'd be surprised how quickly you could adjust to a dane or a mastiff that you love.