[M] Soft or Medium for someone who has had discomfort with other toys

I'm very excited to be getting my first Bad Dragon toys! I am most excited by the material. I'm not a beginner into anal play, but I don't think I'm an intermediate yet. I have a toy with a circumference of 3.5" that I can take comfortably. I have another toy with a circumference of about 5" that is a bit unfomfortable to insert, and after thrusting for a while (which is what I enjoy most) it becomes more uncomfortable over time. I do love the girth, but it seems the material is too stiff, which creates the discomfort. It is a silicone toy (Doc Johnson Ultraskyn), but seems firmer than the BD ones (if I judge it from videos).

I have settled on getting two toys: a Medium size Nox and a Small/Medium size Kelvin (for prostate pressure). But I am really struggling choosing the firmness. It seems most people recommend going with Medium firmness for a first toy. But given my discomfort, I am wondering whether soft isn't a better option. I understand that soft works better with thicker toys, so I think it could work for the Nox. For me, these toys are a large investment because I have to import them, so I kind of want to get it right.

I was hoping to get some insight from others. Thanks!