As an avid spiny eel fan, I feel confident in recommending.... Bichirs. Yeah, that's right.
For the record, I pronounce it biker.
The problem with eels? They're scaleless, sensitive, picky eaters when young, and are suicidal (bichirs are too, but not like eels IME). I consider myself a very good fish keeper, I've worked in the industry, and have cared for many species of fish that most people have never even seen in person. My experience with eels? I have a 100% kill ratio.
The only thing I would recommend eel wise is if you could find and house a large adult spiny eel. Fire eels or tire tracks are great. When they're big, they are almost never shy, eat like pigs, and are very stable. Up until then it's always worrisome.
Bichirs on the other hand are relatively hardy, personable, not picky about food (occasional hunger strikes aside), and are just as interesting as eels.
What species are you thinking about? I know a seller that has some polypterus mokelembembe right now that are pretty rare and stay small, PM me if you want a link to their info.