45mm ?

Nikkor 55mm f2.8 Micro (Nikon says micro instead of macro)

"Considered to be one of Nikon's sharpest lenses ever."

Canon F'D 50 mm f3.5 Macro

"Though ideally correct for close focus work, this is one of Canon's very sharpest normal all around use lenses of its era."
Of course with legacy glass you lose autofocus but you also have a nice solid piece of metal and glass with a very smooth focusing ring. I use manual focus when I shoot macro...

The Canon sells for $150-190

The Nikon sells for $190-250

Of course these lenses are much larger and heavier than the micro 4/3 counterparts but they're fairly inexpensive and there's something very nice about lenses built in the 1970s as far as build quality and feel.

Keh Photo and Camerarepairdotcom are both reputable vendors. I bought "cheap" adapters on eBay....

On another note I recently returned a Panasonic 45-200 mm lens in favor of my Canon FD 70-210 lens.  I found that shooting soccer games (not my photo passion) was more enjoyable and the images looked better to me.  Even though I was shooting manual focus I got a lot of great shots.   Ibelieve I paid $60 for the FD 70-210.

BTW I shoot with a GH-1 and GH-2