Seek vs. Flir One G2...
Well it depends.... with the manufacturer supplied app, the Flir One takes the cake.
However, if you use either with non-traditional apps or with some of the custom software developed here by eevblog members, the situation changes, and either can produce good results.
The Flir One G2 will always have the advantage that you get a visual image as well as a thermal image. As well as preprocessed images (good or bad depending on your use case)
THe newer Seek product will always have the advantage that they offer a focusable lens. If your are doing PCB temperature scans, having to not fashion an aux lens holder is a plus.
If you are doing Search And Rescue, being able to see the visual image as well as the Thermal Image... Flir One G2 wins hands down. But this may not be your use case...
I have both, mostly I use the Flir (One or E4), but I was very active early on in reverse engineering the USB protocol of the Seek... I had great hopes for the Seek and I still think that they have lots to offer in the Thermal Imaging field.
I also was active in reverse engineering the Flir One USB protocol.
Now, both devices can be used without dependence on the manufacturer supplied SDKs.
Lots or really smart folks are working on both platforms and have produced software that exceeds the manufacturers code.
Now that Flir has produced the Boson, the bar has been set a bit higher. Will Seek rise to the challenge or they a one horse show......??
Time will tell.