For sample storage/playback where 90% of the activitiy is reading data there's not much practical difference. I think anything with ~100k IOPS will be good enough. Read speeds don't seem to matter much for sample drives these days.
Where I think the Samsung Pro drives provide a benefit is on an OS drive or swap/scratch drive that requires both read and write. I use Samsung Pro drives for those and a mix of WD and Samsung EVO drives for samples.
The Samsung EVO drives are pretty price competitive, aren't they? I just bought a couple more and I think they were pretty much the same price as the other major brands.
Also, why external? I haven't looked in a while but internal drives historically provide better performance and modern laptops have plenty of expansion (I think?). I have 5 TB of NVMe SSDs in my laptop. No cables required!
I’ve never had a failure with any SSD and I’ve never much paid attention to brands. I think I acquired my first in 2013. That’s in my laptop as the system drive. The second is now functionally retired because it’s 512GB. The other 8 are all 1 or 2 TB. In the meantime I’ve had 5 HDs fail during that same period.
It is possible to upgrade the original drive and also add a second drive to an iMac, but it's not for the faint-hearted (see guide below). By going internal you may gain a little speed too - up to 550MB/s (externals tend to be slower).
I had to strip mine down to replace a noisy fan - it looks harder than it actually is.
Interesting, because I have purchased numerous SSD drives for both myself and others, and the only one I've ever had fail was also an OWC, (I do not recall the exact model name) that I put into an older MacBook Pro. So I've not considered purchasing an OWC ever since, even though it could have just been bad luck.