Bad Dragon's products are somewhat expensive, but they'll last practically forever if you take care of them. I've been happy with mine. They have a flared and unflared horse dildo. I would recommend getting a cumtube because it makes lubing a lot easier (and it's way fun to fill yourself with a load

. They even have whitish cum-like lube. I would also recommend medium softness for a small or medium dildo and soft for a large. But, you might just want to read the literature on the site and site forums.
Chance Unflared is the ultimate anthro horse sex toy. Sculpted by hand with a medial ring and bulbous head, you'll want to grab your saddle and hop on.
bad-dragon.com
Chance Flared is the ultimate anthro horse sex toy. Sculpted by hand with a medial ring and bulbous head, you'll want to grab your saddle and hop on.
bad-dragon.com
In my opinion, a small unflared dildo is too small. A cheap, readily available dildo is fine for warming up and stretching, and then use the bigger Bad Dragon dildo when you're ready to go.
This is just my perspective, so take it with a grain of salt. Good luck! Feel free to ask other questions!