Advice about buying an external SSD or flash drive

I am considering buying a portable device to store files, taking advantage of Black Friday prices. My candidates are:

-Crucial X9 Pro 2TB SSD. Up to 1050MB/s. About 120 euros.

-SSD Crucial 2 TB. Up to 1050 MB/s. About 125 euros.

-Crucial X10 Pro 2TB SSD. Up to 2100 MB/s. About 200 euros.

-SanDisk 2TB Extreme SSD. Up to 1050 MB/s. About 130 euros.

-SanDisk Extreme PRO 512GB flash drive. Up to 420 MB/s. About 80 euros.

My first doubt is whether I should consider a flash drive or an external SSD. An external SSD could give me more performance, but I don't want to lose portability. In case of choosing an external SSD, my doubt would be if paying the higher price (i.e., the Crucial X10 Pro) is worth it.

Any tip is welcome!