Hey, I'm a fellow Daemons player so try and help. What I write is just suggestions based on how I've found them. So here goes:
OK I feel you need to bulk out the troops a little. Skulltaker with 20 bloodletters or 2 units of 10. They are nasty and will cause carnage. I would like to see a unit of 20 or so daemonettes. They're great against anything fleshy. I'd recommend pink horrors. Great shooters to cut down troops. Add a changeling for 5 points for the Glamour of Tzeentch ability. Well worth the points! Plaguebearers are good for soaking up shots and holding objectives.
As for you HQ's, I've not used either. But the Lord of Change would be good against an armoured opponent. I like to use a Bloodthirster, but that's simply because I have the model and like Khorne.
Juggernauts are fantastic, but 2 will get shot down very quickly. 3 minimum, 4 would be better. Another Elite to never leave home without has to be Flamers. Do yourself a favour and get some. You don't need lots, 3 will do the job perfectly. Anything on foot is soon left as a smouldering pile of ash. Better against units then single models simply because you get more hits.
Soul Grinders provide much needed artillery to a Daemon army. It's good you have 2 as if you only use 1, it's the first thing to be shot at. Daemon Princes are great too, especially against vehicles or indeed other monsterous creatures. A very versatile unit as you can tweek it to do several things.
Well, I hope that helps a little. Look forward to seeing what lists you come up with for future games.
All the best.