Classic wow has only about 240k people active in the last 7 days according to one site that monitors active players count, thats not too big, niche multiplayer tank games has more than that.
This smells fishy.
Also implying WoW pvp is any better, well...
But back to the topic, OP should give a try WoW and see it himself how it is. The fact is fast combat in WoW has been compromised by the lack of skill diversity and gameplay, which makes you spam few same skills over and over. No one who actually plays wow will tell you that their game class design is good, it gots so much worse after legion and a ton of people left the game because of the changes implemented to make the game more casual friendly.