I bought some of the Case Logic hard drive cases which I continue to use today. The cases outlast the drives.
Here is a link to those cases in case you want them.
I haven't done a lot of research on hard-drives. I have read about which ones are doing well, but when I get to the store often their are newer models available.
My preference is the firewire connection hard drives. But with the prices on these so high and availability of choices so low, I have only a few of the firewire drives. Most all of my drives are the newer USB-3 or the older USB-2.
Whatever at the time is the largest hard drive with a competitive price is what I have been buying and most of the time I just drive to Frys, which is close to my home in Roswell, GA.
Two external hard drives
When I travel I always carry two external hard drives. One is a complete mirror backup of my Macbook Pro 15" computer. I use SuperDuper! for cloning my hard drive. I do this about once a month. Usually the backup is prompted by my next trip.
If I ever have trouble on the road I can do a complete reinstall from this hard drive or I can launch from this hard drive by holding down the option key when starting my computer. By choosing the external hard drive I can now run off of it. The advantage here is now I can run DiskWarrior to clean up any problems on my hard drive while I am on the road.
I have had to save my bacon more than one time with this backup.
The other hard-drive is for images and photos. All my memory cards are ingested using PhotoMechanic and the destination is always the external hard-drive.
I will leave you with one last tidbit. I also have CardRaider Photo Recovery for those times that I need to recover images off my memory cards. I have accidentally mixed cards up and format them before I ingested them. I thought I had one card in my hand and actually had reversed them. This software is for the Mac.