I once wrote an article titled "Why 4 x 16 is Greater Than 64". That was a few years ago but the premise still holds true.
As many have pointed out, using a smaller card means that in the event of a failure or loss, you won't lose as much of your work.
I am tempted, now, to update that article and re-title it as, "Why 4 x 16 is Greater Than 128".
That's because I would advocate for changing cards - and backing them up when you change or charge batteries.
If someone has gotten more than 16 GB of data (pictures, video) on a single battery charge, I'll be happy to revise the title. ?
Multiple lower capacity cards are slightly more expensive than a single high capacity card.
So, what do I use? 64GB mostly - because I have a lot of them. When I shut down because I'm done flying out to change batteries, I swap cards. When I get to a computer, I backup the cards that I've used. I use Adobe Lightroom Classic. Then I put them back in rotation but I don't delete anything yet. When they are getting full, I format them after backing them up.
My computer backs up to the cloud, so I pretty much always have two copies of everything until I get around to editing and purging.
A raw image such as DNG takes around 1MB per Megapixel. Jpeg is much smaller, depending on compression level but allow for 100KB per Megapixel. Video depends on resolution, frame rate and compression algorithm but you can expect to use about 300MB per minute for 4k 30fps. With overhead, that should give you almost 30 minutes of recording time on a 16GB card - about a battery worth... A 64GB card would allow over 2 hours - much more at 1080 30fps.
So... 4 x 16 is still greater than 64 and possibly also greater than 128. And 2 x 64 (backed up and swapped each time the drone is turned off) is definitely greater than 128. ?