Best GPS shield?

Hey guys, I’m looking for a good GPS shield to test and validate an idea before building a custom embedded solution. We want to put GPS trackers in packages, measure some environmental data and push that data to the cloud (sigfox/Lora etc). I’m pretty comfortable with all the other bits but I’d love to hear your experiences in using various GPS shields or serial/i2c devices before I buy a bunch of Dev kits. Having an arduino stackable shield is not important.

Because the units will be in a box in a truck sensitivity is super important.

Because we’ll likely be making the embedded versions in the 100s, availability (on mouser etc) of the chipset is also a factor.

Thanks!