In many ways, the Lumix GX9 takes two steps forward over the GX8, but one step (maybe half a step) back.
The removal of the optical low-pass filter means Lumix GX9 delivers excellent detail, with images looking that bit sharper than those from the GX8, while the smaller form factor compared to its predecessor hasn't seen the quality feel of the camera sacrificed.
That said, it's disappointing to find that the GX9's viewfinder and screen aren't quite a match for the older model, while it's also a shame that the weather sealing has been dropped.
Comparisons with the GX8 aside, the Lumix GX9 slots in nicely above the GX80/GX85 in the Lumix mirrorless range. It's similar in size, but offers a few more features and improved handling, thanks in part to the dedicated exposure compensation dial. While there's perhaps a little too much reliance on the touchscreen interface for some tastes (especially when selecting your desired AF area), the Lumix GX9 is a nice camera and a very solid performer – it just doesn't do quite enough to stand out from the crowd.
Panasonic Lumix GX80/GX85
The more affordable sibling to the Lumix GX9, the GX80/GX85 features an older 16MP sensor, while it also lacks the GX9's tilting viewfinder and dedicated exposure compensation dial. That said, it's quite a bit cheaper if you're looking for a compact mirrorless camera that won't break the bank.
Read our in-depth Panasonic Lumix GX80/GX85 review
Perhaps the closest rival to the Lumix GX9, the X-E3 from Fujifilm is a great camera when teamed with a prime lens or two. The 24MP sensor delivers stunning results, and while it doesn't have the tilting EVF or rear screen found on the GX9, the controls are that much more satisfying to use overall.
Read our in-depth Fujifilm X-E3 review
Olympus OM-D E-M10 Mark III
While it looks more DSLR-like in design, the Olympus OM-D E-M10 Mark III is one of our favorite mirrorless cameras. Like the GX9 it's based around a Micro Four Thirds sensor, and the controls and finish are excellent, while the EVF is great for the price.
Read our in-depth Olympus OM-D E-M10 Mark III review