Whereas I think corruption was terrible. It was completely random in how you got it for quite some time. It seriously advantaged some specs over others (warriors, for example, did hugely well because the beam did damage based on character health and warriors have substantially more health than other melee DPS). The means of getting it (running visions) also favoured some specs over others. Oh, and because you had to run visions over and over to amp your cloak up so you could run them at the harder levels, if you fell behind it was very, very hard to catch up until it got to the point where everyone had all their stuff so they weren't a moving target any more (but it was still seriously time consuming).
On a more personal note, the visions were effectively timed content, and mythic+ runs are quite enough timed content for me, thanks - I'm not a fan of gogogogo or content that requires it. The only good thing was that friends could drag under-equipped mates through the content and help them out a bit, though in doing so they'd be spending their time on runs that were easier than they'd probably prefer, so even that wasn't wonderful.
I cannot look back on corruption and visions favourably.
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Once the stat rot had set in, say halfway through levelling in BfA, Resto Shamans did more DPS than Elemental, because all bonus effects that gave them damage were gone and Resto's basic attacks did (and still do) more damage than Elemental's.
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Give out the new shinies as a mixture of new top-end stuff, and new options in old slots (with the old options staying there). That means a lot of the new 'power' is growth in breadth (choice) rather than in depth (raw output).