I don't have any modern day choices but I would have loved to see Bones Jones versus peak Anderson Silva (not the washed version)
I think Bones would have won with the superior wrestling but Spida would have had such an edge in quickness.
I also would have loved to see Bones versus Fedor.
I think those 3 are in the short convo GOAT between 185 and 220.
On the women's side my fave fighter was Miesha Tate and I met her at a fight but I saw all the women's fights I thought were poignant.
My fave male fighter was Arlovski and I saw him fight everyone to varying results.