Rewind a few years and I thought the Lumix 25mm f1.7 was an amazing budget lens, really, its cheap, produced a good picture quality...it had an f1.7 aperture. And then I bought the Sigma 30mm f1.4 and oh boy!
Key differences:
Sigma Lumix
30mm (60mm full frame) 25mm (50mm full frame equivalent)
f1.4 f1.7
Metal body Plastic
Medium size Really tiny
9 rounded blade 7 rounded blade
If you want to find out more, check out this head to head comparison with the Sigma vs the Lumix for MFT with some side by side comparison shots.
Get the Sigma 30mm f1.4 for MFT here - https://geni.us/Sigma30MFT
Lumix 25mm f1.7 MFT - https://geni.us/Lumix25mm