I’ve played every Screaming Eagle except for the Duncan Hugo Z Hor. I have played the original Hugo Z Hor, though, so I will try to touch on that as well as I can.
The Vendetta is my least favorite of the Screaming Eagles. The shape is rather sharp and uncomfortable and the response is just awful. The weight and size are both at a nice middle ground though, but I’ve thrown one on a couple of different occasions and can’t bring myself to throw it more than once or twice.
The Mayhem is the exact opposite in my mind. It’s my absolute favorite Screaming Eagle. It’s a very comfortable, natural shape that’s a great size (51mm) between the common 50mm diameter and the 52-53mm mark. The Mayhem is ridiculously smooth, stable, spins long, feels great on the string (is on the lighter end), and comes with a great stock response system that is reliable and feels very comfortable during use. It comes with an A bearing that really fits the yo-yo well, in my opinion. even though the yo-yo has a gap smaller than 4mm, it doesn’t feel too small and won’t snag once the pads are broken in. The finish is also superb: not only does it look beautiful (especially in the sun), but it grinds like a charm (and has a nice IRG as well).
Next on the list is the Momentum. Many people say that this yo-yo is the Mayhem with stacks. Don’t believe this. They are both similar in size and shape, but do have some subtle differences in play. The gap width in the Momentum is a little larger than the Mayhem as a result of the D bearing. The curved shape flattens out at the edges instead of continuing the curve of the Mayhem. It’s a good solid yo-yo that I wouldn’t hesitate to recommend if you really wanted stacks. Personally, though, I’d forgo the stacks and stick with the Mayhem if it were between the two.
The Diversion is one I’ve played very recently (with the caps on) for only a very short period of time. I didn’t like it as much as the Momentum or Mayhem because I much prefer lighter and undersized yo-yos (and the Diversion is BIG and HEAVY). Even though it’s not my style, I can appreciate the excellence that is the Diversion. It’s very stable, has epic spin time, and a great response set up (C bearing and pad recess) that works wonderfully with the gap. If you like large yo-yos, go for this.
The last yo-yo is the Hugo Z Hor. Unfortunately, I haven’t played the Duncan iteration of this yo-yo, but I owned the original for quite some time. This yo-yo is much smaller than any of the other Screaming Eagle yo-yos (48-49 ish mm in diameter). The original Hugo Z Hor did feel tiny in your hand - but it didn’t feel cheap. It was a solid, smooth, stable throw, but was very generic in shape and play. The gap was a tiny bit snaggy, but Duncan has widened the gap in their version and replaced the original C bearing with a D bearing (which I feel might help out a little bit). They’ve also changed the original silicone groove to a pad recess because we all know that Duncan = pads. 
That’s not necessarily a bad thing, but just something I thought would be worth noting. The spikes on the side of the original Hugo Z Hor were awesome. If Duncan has preserved that, you can look forward to some fun.
If you have any other questions, let us know. I hope this helped.