Experience with USB hard drive docks (I'm full of questions)

What are some advantages of USB hard drive docks and enclosures over external hard drives? OR the other way around?

Looking for opinions, and maybe some favorite/recommended brands and why?
Thanks!

I have a dock simply to save me from opening up the case, for testing other hard drives etc. Any permanent storage is installed in the case.
What is your intended use? Is is just portable storage, or is it periodic system backups/clones etc?

Your usage and existing kit makes quite a difference to the choice.

If you have a single 3.5" HDD and more than one computer to plug it into then you would probably be better off with a caddy for the purpose, ie one bought as a complete external HDD or a caddy that you fill and seal.

If you have a combination of drives and computers, then it makes sense to have a caddy that allows you to swap between drives as well as between computers. But you then need some way of storing bare drives safely away from coffee cups and little fingers.

If you only have a single computer (and not a laptop), then a dock built into the chassis would be more convenient.

Whether using an external caddy or a dock built into the chassis, the logical connectivity is the same (eSATA would be much quicker than USB2 but you would also need to make sure the OS supports hot-swap - AHCI in Windows) so performance will be similar.

However, an external caddy would require its own power supply as well as the data cable unless the drive is a 2.5" variety.

Personally, I have a PC chassis with a dock built into the top as well as a hot-swap caddy. That allows me to pop any one of a number of spare drives I have into either PC or even the laptop so I can swap large backups between machines. It also means that if a friend has a problem with their machine, I can extract their drive from their machine and connect it to mine to retrieve data without having to resort to a screwdriver on any of my machines. Both the built-in dock and the external hot-swap caddy will accept 2.5" or 3.5" drives.

I have found that the make of most kit (apart from the cheapest no-name makes) doesn't matter. They are all constrained by the speed of the interface of the HDD itself and use the same basic technology to deliver the data transfer. Once you get over the novelty of new ownership, then the look really doesn't make any difference either.

Once you have decided what kind of kit fits your needs, then I would suggest price is the most important deciding factor between similar models from different manufacturers.

I recently added one of these to give me a tidier system. I was using an external before but this also gives me two front USB 3.0 ports as an added bonus.