USB 3 vs. TB2 for transferring files/videos?

If the external drives are standard HDDs (not SSD), USB3 will be fine. If the external drives are SSD and you have multiple drives, thunderbolt.

USB3 has a limit of 640MB/s so you'd need 5-6 standard HDDs on one USB3 port in order to max out.

 

Get raid drives for the best performance. I've been recommending the 4tb sea gate backup fast drives

 

I have to disagree in one point:
You can use the speed of external SSDs via USB 3 if you buy a UASP capable USB3 enclousure.
A Samsung 850 EVO SSD has read an write Speeds around 480 MB/s, so you can even use USB 3 for that.

But I agree with you, that if you use more HDs or SSDs in RAID mode, Thunderbolt would be the way to go.
But you always have to look at the specs of the Thunderbolt enclousures, because there are many out there that internally use cheap Serial-ATA Controllers, so you have no real benefit of thunderbolt at all.

 

Ah yes I forgot to mention to get an enclosure with a decent controller like an ASMedia ASM1153E or better that supports UASP.

 

1: Correct, although then again you actually have to be reading/writing to all five at once in order to bottleneck USB3. 4 disks at idle and 1 reading at 90MB/s won't bottleneck it.

2: Some people have experienced power dropouts and random disconnects through USB3 however that is down to using a poor quality enclosure or drive. In my opinion, unless you are in a situation where you will bottleneck USB3, thunderbolt enclosures aren't worth the $100+ extra just for the enclosure. There are some minor benefits to thunderbolt such as full trim support on SSDs (it can be enabled on USB3.0 but it's not guaranteed) but on standard HDDs there's no real point.