Top five based on what criteria? Design aesthetics? Features? Historical relevance? Portables? Standards? For example, the Selectric models are incredible machines from a performance perspective, but there's absolutely nothing sexy about them. On the flip side the Lexikon 80E is a work of art, but not a machine I'd pull off the shelf for when productivity is the main goal.

 

 

Well, unless you're willing to risk and pay for shipping (electrics are extremely heavy), your choices will realistically be limited to what's available in your geographic region. The nice thing about those older electro-mechanical models is that most of them use regular ribbon, the same as you would for a mechanical typewriter. 

Given the brands that you listed I have to assume that you're in North America. If you are okay with a standard, you should be able to find pre-Selectric IBM models like the C and D. They're quite nice to use and still look like a 'normal' typewriter when compared to the later IBMs. 

For portables, I'd definitely invest in a Smith-Corona Electric Portable if you ever come across one (the first portable electric typewriter in a 5-Series case). Any of the second generation (6-Series) models - late '60s to very early '70s - are reliable workhorses, and some of them can look quite nice too.

I'm also partial to the late '70s, early '80s Olympia portables that were made in Japan. Solid design and performance, and were also fairly common in North America.

There are of course myriad other electric models that you might come across. Repairing electric models can be a more complex thing, so if you're not comfortable with such an undertaking I'd strongly suggest fully testing any machine that you are interested in before you buy it. Power it up, check every key's action, and all the other functions/features of the machine first. Some problems can be very minor, others a real headache. There's no guarantee that a working machine will work more than a few hours after you get it home, so keep your budget very modest and it will certainly be worth the risk. Most of the electrics that I own were purchased in the $10 to $30 range.   
 

I'd second the recommendation to look for one of the 6-series Smith-Coronas, like the Electra models. We had up one of these growing up, an earlier one that still had the manual line spacing lever -- which actually I think I'd prefer, since the electric carriage return is rather violent and noisy. And it's one less thing to go wrong.

Robert Caro, justly renowned biographer of Lyndon Johnson, has been in the news a fair amount lately because he's published a sort of memoir, called "Working." He has used nothing but 6-series SMC electrics for decades, and types everything himself. 

I would never say anything against the A and B models; I only mentioned the C and D because they seem to be easier to find - at least in my part of the world. And speaking of IBM, I just happen to be working on a Memory 100 at the moment; because of its complexity it's a model that I wouldn't recommend.