... That`s a VERY difficult question to answer. Let me indirectly provide an answer...
I don`t think there is any song (not solo) which is particularly difficult for me. And that might provide some hint of my skill level. On the other hand... I could really suck, and just think I play well.
I can`t think of a single song that is incredibly complicated, but I do think different music styles have different technical levels. For example, I am definitely a "Rock and Blues" style drummer.
I find Jazz to be a style of music with a high technical level. There are multiple patterns being played, on each limb (legs & arms). And in many cases, the playing style is very light to the touch. Actually as I am writing this, I am thinking I am not very clear about what`s a difficult song...
In the past I have played in the symphony (some sheet reading skills which are not completely gone), swing band (a lot of jazz techniques), rock band, and even a Vietnamese band!
So what would I consider a difficult song??? I don`t have one. But I can pick all the typical, top tier drummers and say... Those performers are hard to match. I won`t say follow, because following is easy. Matching skills and exceeding others is very difficult.
Vincent Wilcox (a.k.a. KRAKR)
My band: Letters Make Words