I'm tossing around ideas for a second M4/3 lens, whether to go with an old standby that I've owned before - the 17/2.8 and 25/1.8 are "prime" among those - or be more adventurous and get one of the well-regarded lenses that I have considered in the past but never bought, like the 45/1.8 or the Pana-Leica 25/1.4. Obviously focal length is a "prime" consideration (okay I'll stop!), but in addition to that I am thinking about the lenses that just "work" so well in a more subjective fashion with OMD cameras. Like the way the O25/1.8 just fits (sizewise) and renders beautifully on the 16mp sensors, as it did on my EM10 in the past (and GX85 too, naturally). And, the Pan-Leica 25 regularly has its praises sung - not to mention how welcome f1.4 is on the M4/3 sensor. It opens up creative possibilities with the aperture, much like the Sigma 30/1.4 did, though I eventually didn't appreciate how large that lens felt on a small body.
But then there's the more holistic question of how to build a small but capable kit. Right now I have what some might call a good one-lens solution in the 20/1.7. But the problem with one-lens kits is that, when you expand either up or down in focal length, the one lens becomes less ideal of a solution. If you get a longer lens, you start to wish the 20mm was a bit wider; if you get a wider lens, you wish the 20mm was a bit longer. A one-lens solution often doesn't automatically become a two-lens solution when you add a second lens.
So what to do now? I would actually really like to try what has worked as a two-lens kit for a lot of people: a 17mm and 45mm. the 35mm-equivalent straddles wide and normal fairly well, and the 90mm-equivalent is long but not so long as to make one struggle to implement it. But the 40mm-equiv lens I have now is a tad too tight to work in place of a 35-equiv, and buying a 17mm in addition to the 20mm seems like overkill (even though I know well the difference in rendering and character between the 17/2.8 and 20/1.7 and there's room for both).
I could branch out to not one, but two lenses that would be new to me: the 17/1.8 and 45/1.8. That would probably be a fine kit. But I am sentimentally attached to the 20mm, and know my track record for reacquiring it so I should just hold onto it! Maybe I will just get the 45mm and see how well I can make the 20mm and 45mm work, with the GRIII as my wide angle backup. That seems reasonable.