If the only reason you stopped was because of the "grind", then any time from now should be ok to get back in. HOWEVER, if you didnt like the "grind" is because you didnt enjoy the gameplay or the progression, or the systems, or something along those lines, then stay away - nothing has REALLY changed. If you can afford 1 month (either disposable income or gold) then absolutely go for it - fun is subjective, and its impossible for us to say what you will or wont enjoy.
The only thing I can say, is that although subjective as i said, if you didnt enjoy the core gameplay loop, that hasnt changed.