Hey Tremble,
Firstly I'll agree on the wrathmongers. As glorious as their stats are, I can't stand their figs and never put them in my army haha.
If you're thinking of going a cavalry list, and already have juggs and a lord on a jugg, perhaps consider taking the Brass Stampede betallion. You'll need 3 squads of juggs, but it means they get better charge distance, if any unit (friend or foe) is killed and their 4+ to do mortal wounds in the charge doesn't need to roll to go off. This helps a lot more than it sounds. You'll be surprised how much their 8" move could do with that awesome charge buff.
I'd take 5 knights in a unit if you're taking them at that points limit. The reason you'd take larger squads is so that you can activate more models at a time, which is why it can be quite powerful, but at 1000pts, I don't see the need for more than 5 in a unit.
Bloodwarriors are glorious. Take them, love them, never let go of them.
The secrator is kind of hard not to take. In every list I make, I can't see a reason not to take him. His 18" bubble is massive. It may take a couple of turns to run him to a good place, but as soon as he opens up, he is more than worth his point cost.
Reavers can either be useless or amazing. If you stand them within 12" of your secrator, they're getting 3 attacks each. Give them the -1 rend axes in a unit of 20 and that's a rediculous amount of pain. Not to mention how much you can pump them up further in higher point games with other units/battalions. I'd consider taking some if you have the points spare and want some. They'll die in droves, but even 5 of those suckers can do some work.
I've not used the marauder horsemen but I want to get some. I think they seem cool because they're basically all we get as ranged units (apart from the slaughterpriest), and their ability to run, shoot and charge all in the same turn seems incredibly mobile. I'd use them as fast harasser units to basically go wherever you need a bit of extra firepower. They get into danger you don't want them to be in? Just run off and start harassing a different unit.
If you can't fit all of that into a 1000pts list, just pick the stuff you like most. The betallion is probably an extra thing to add if you have the points spare as, at this point limit, more units is probably better than that battalion benefit.
Hope this helps