Good question. I have old and new models in my collection, and rotate them all for cleaning duty. Emotionally, I'm connected to the older metal-bodied machines, because I grew up with them, but I do like using the newer ones as well (as an arthritis sufferer, the plastic machines are sometimes easier to use).  The new ones clearly are somewhat more powerful, but if you connect an airtight vinyl hose and L-shaped power nozzle to the older ones, they can do an excellent job as well. In short, its hard to choose one over the other.

Maybe in your case, since you mentioned you don't want to keep a lot of vacuums, you might be better off with a couple of the new ones, and then the hoses, attachments, etc, will be interchangeable. I know a lot of people don't like plastic machines, but I can't quite go along with that...plastic machines have been around now since 1973, and some of them are still going strong.

Either way, you'll be using an Electrolux, and it doesn't get better than that

Don't own a plastic machine .... I'm somewhat allergic to plastic so I shy away from them.

I have a model XXX, Super J and Ultralux, all in pristine condition.

The Super J is my favorite lux machine .... the one I grab when a job calls for super suction.

I think it was one of the best in that series of luxs.

I definitely prefer the metal machines.

psf

I much prefer my vintage vacuums.  For that matter I'll take vintage over modern for just about anything in and around the house, except maybe for central heat and ac!  Although, nothing warms me up on a cold winter night like a fire in the woodburning stove. 

I own a Lux 2100 but have used it all of maybe 5 minutes in the last 5 years.  My older Electrolux vacuums serve my needs perfectly, right along with my older Kirbys, Hoovers, etc.  The only "modern" vacuum I really enjoy using frequently is my Henry, who is far too powerful for his own good (animals and small children beware!) and he's just too cute for words.