What Pana Lens is worth considering Over Olympus lens if you use OLY body?

The Pana 20mm f1.7 can be compared with the Oly 17mm f1.8. Pana is cheaper, possibly sharper in the center, but slower to AF.

The Pana 14-42mm should be compared to the Oly 14-42mm lenses. Not to the 12-50mm. It is a different class of lens.

The pana 12-32mm can be compared to the 14-42mm mini lens. The Pana is wider and sharper.

The Pana 12-35mm f2.8 can be compared to the Oly 12-40mm f2.8. The main reason to go with the Pana is the size. It is smaller.

Same for the macro lenses: Pana 45mm and 30mm macro lenses are much smaller than the Olympus 60mm macro lens.

Pana 25mm 1.4 can be compared to Oly 25mm f1.8. Pana is bigger, more expensive, but faster than the Oly.

Pana 100-300mm f4-5.6 can be compared to the Oly 75-300mm f4-6.3. The Pana is a tad faster, but the Oly is smaller and wider. That said, the OIS is still a nice addition for such a long lens, even with IBIS.

The Pana 8mm f3.5 fisheye can be compared to the Oly 8mm f1.8 fisheye. The Pana is smaller and cheaper compared to the Oly 8mm f1.8, but the Oly is much faster. Not sure about IQ.

The Pana 7-14mm f4 can be compared to the Oly 7-14mm f2.8. The Pana is cheaper, much smaller and lighter, where the Oly is weathersealed and faster, and does not give blue reflections on Oly bodies.

All in all I think there is much more than OIS or price to determine if a lens suits you. There are interesting Panasonic lenses for Oly camera users!