Quick backstory. My group of friends retired from mythic raiding with the launch of bfa. Some quit, some decided to give it until first major patch. Our core m+ team from last expansion stayed, except our healer. I chose ret as a main, our tank stayed blood dk. At the end of legion we were clearing 20s - 22s. Now, we've had to swap the dk to frost and me to prot to clear over 15s. Am I missing something here? I keep hearing how strong blood is. I haven't leveled one yet to know for myself, but is it majorly different than legion blood dk? Is my friend a product of gear masking his ability at the end of legion?
Main question: what do you all think is the stronger m+ tank and why?