That's a bit of a tough call since the models are really so similar, even from metal to plastic.
Obviously by my name, you can tell I am a fan of the Diamond Jubilee, so that would probably be my top pic. I've never had a motor problem. I really like how the bag door and cord winder/rear cover have a contrasting color, versus most of the other 1205-based models that have body-colored ends and/or white ends. That being said, I'm also really fond of the Ultralux Classic with that deep blue paint.
As for the plastic body models, my top pic is probably the Guardian Ultra. I love how it's the only classically-styled Lux to ever have a fully-sealed HEPA system (WHY didn't that setup transfer to the Legacy and Classic when the Ultra was replaced???). I also think that the rounded, silver top with its pin-hole grille is just extremely satisfying to look at. I could kick myself for selling the one I bought (pic attached for reference). My second choice would be some version of the Epic 6000/Lux Legacy. It looks really nice in the original blue/white color scheme (like the Ultralux Classic), but I'm also partial to the all-white version from the late 2000s/2010s and the current black version. I'm not wild about the gray version from the mid-90s nor the white/light blue version from the early 2000s.
The Guardian Platinum seems like a great machine, but I cannot get over the fact that it isn't even made by Aerus in Virginia like the Legacy and Classic. To be honest, I really don't even know for certain its heritage... did Aerus REALLY participate equally in engineering it, or did they just throw in some cash to license a copy of the Lux Intelligence, add their own accessories, and basically phone it in? Either way, it's not a purebred Aerus/Electrolux product. And I've read good things about the Renaissance/Epic/Guardian machines, but I've never owned one, they're pretty far removed from classic styling, and they seem to scratch up pretty easily compared to other vacs from that same time frame.
