Olympus 12-100 mm f/4 IS Pro
I bought the 12-100 f/4 just a short time ago and it is rapidly becoming my favorite lens. It is clear, sharp, and the 12-100 range (24-200mm in 35mm film format) covers most of my shooting requirements. The combined in lens stabilization and in body stabilization in my OM-E-M1 Mk II is astonishing, allowing hand held shots at 100mm using 1/5 second or even less.
The lens is large, larger and heavier than I expected, but it is well balanced on the camera. It feels comfortable on the E-M1 Mk II. The lens does not creep when carrying the camera and lens on a strap and it really does not feel that heavy compared to the 12-40 f/2.8. It may still be too large for a tourist setting as it does attract attention. That has not kept me from carrying it in public gardens and the results have been fantastic.
It is not an inexpensive lens. The long zoom range and the general quality of the lens I think are worth the price. I have used it in bad weather both traveling and in workshops. Having such a high quality lens that you don't have to change makes it worthwhile.