It's an open-ended question. To me, the discussion behind it makes the thread better. So there is no right or wrong answer. And if you want to say that this WR is the best in the last 20 years then I'd love to hear the explanation. It's ok when you just rattle off names like Irvin, Moss, Harrison. BUT it makes the discussion better when you say why.
And your right, numbers don't translate through eras. But I think people who respond to this thread already have that understanding. There are already votes in this thread for Don Hutson. If you looked at his numbers, he wouldn't even stack up to TO. BUT if Hutson played in TO's era and adjust Hutson numbers to the modern time, Hutson's number would dwarfs TO's.