What we do have is pretty good except for a couple lenses that are exceptionally good like the 20m pany but it would be nice to have some real high quality alternatives that are AF. I guess if we want really decent glass we have to go Leica, Zeiss and Voigtlander manual focus.
Micro Four Thirds is a much younger system, don't expect a similar amount of lenses to choose from.
However, I am convinced that there are some more than only decent lenses available. Of course, there is the 20mm, but don't forget the 9-18mm, which is a great lens, and the 7-14mm, which is great, too. The flare resistance of my 9-18mm is simply exceptional, much better than any consumer wide angle zooms by Nikon and Canon I know of. It is sharp even in the corners, which you don't get from all wide angle zooms of Nikon and Canon.
We have a macro lens, which is as great as Canon's or Nikon's macro lenses, and we have some very fine zooms. Neither Nikon nor Canon offer such a fine super zoom like Olympus' 14-150mm or Panasonic's 14-140mm. You have to accept much more compromises, if you buy Canon's or Nikon's super zooms.
Panasonic's 100-300mm is said to be a great lens. Howsoever that may be, I have seen some raw files made with the E-PL1 and Olympus' Micro Four Thirds version of their 75-300mm, which are so astonishing, that I will most probably buy this lens as soon as winter has gone. You cannot buy any comparably light lens matching the equivalent range of Olympus' 75-300mm from Canon or Nikon, because there is no such lens and there cannot be such a lens (I don't want to carry such a heavy lens like Canon's 100-400mm, which offers the same range on a camera with an APS-C sensor).
I love my 17mm by Olympus, which is one of the most underrated lenses. It is very light, sharp enough, and I really love the aesthetic quality I get from this lens. But I can say that from the 9-18mm, too, and there are even pictures I made with my 14-150mm, which have this special aesthetic quality I love so much.
These lenses are extremely light and offer a very high image quality, at least if you don't get defective versions (which can happen with lenses of any manufacturer). One has to look at all aspects. Any lens is only as good as it fulfills ones individual needs. Canon's 100-400mm or Nikon's 80-400mm or Nikon's 200-400mm may be better in some respects, and I am sure they are, but unless I want to carry that much during my hikes, they are nowhere near as good as Olympus' 75-300mm, which I would take with me the whole day long. The same holds for other Micro Four Thirds lenses, too.