WoW has improved a lot on my Mweb account. Back in the day when EU WoW was just released, with my Mweb account I used to get 800-1500ms. Today, I get 300ms+- with my 4mb uncapped account which is a vast improvement. Mweb also recently had a lot of problems with WoW, massive packet loss, 20kms latency etc. which seems to be resolved, so they have been working hard at improving gaming on their network.
All that said, the best WoW experience still requires tunneling/proxy services, regardless of ISP, shaped/unshaped. I use BattlePing which gets my WoW latency down to a constant 170ms and delivers maximum stability. This shows the potential of what ISPs could deliver without the need for such services if the traffic was routed and prioritized optimally.