Best SSD portable

Hi!

I have a iMac 27 "Late 2012 with USB 3.1 Gen 1 + Thunderbolt 1.

I would like to buy an external SSD portable hard drive.

I was thinking of the Transcend StoreJet 500 because it seems to me the only one with a Thunderbolt 1 port that reaches theoretically:
Read: 440 MB / s
Write: 300 MB / s

Then there are an infinite number of other SSDs like the
- Samsung T5
- Western Digital My Passport SSD
- SanDisk Extreme SSD

But I'm confusing myself with the real performance they achieve compared to the Transcend StoreJet 500 because they always mention USB 3.1 Gen 2 and therefore I can't understand connecting it to USB 3.1 Gen 1 what performance you get.

I believe I should choose Transcend StoreJet 500 because Thunderbolt 1 is superior to USB 3.1 Gen 1, don't you think?

 

OK, I think I go for Samsung T5 or SanDisk Extreme SSD, anyway USB.

Samsung T5 with USB 3.1 Gen 1 get top performance, or better when connected to USB 3.1 Gen 2?

Last question, what about the situation about Thunderbolt 1 and double channel about simultaneous Read/Write data?

 

Samsung T5 ordered, hope the best decision.

 

HFS+ or APFS format?

 

Incredibly satisfied with my new Samsung T5, even faster than my internal Fusion Drive, maybe because it's still full of data.

I formatted it in APFS making it also bootable.

I hope to continue to appreciate it with time.

At the passage of Apple's new macOS in September-October, I believe I will split the Fusion Drive.

 

500 GB. I want to use SSD for normal use ad an old Western Digital 1 TB as data archive for documents which I don't use frequently.