BD Fenrir or SBF Tyv

I like me a good knot, like the kind that really pops in and ties in you. I have a small nova and med nocturne and while the knots are enjoyable, they seem to want to come out right away on their own. I'm wondering if anyone has any experience with both of these and can offer an opinion. I'b be considering either a small fenrir or a medium tyv. What are yall's thoughts?

 

I don't have any experience with Fenrir but I love Tyv! It's the only toy that's tied for me so far. Personally eventually I will have both since I'd like a Fenrir with a cumtube which Tyv can't have but its still a really great toy! The texture on it is amazing.