Yeah footsloggers, sticking it to the man. You make me proud.
I like the second list much better than the first, the split Obliterators let you have better flexibility for Tank Hunting, which is important when you aren't putting your short range AT exactly where you want it.
I think a loadout on your Plague Marines like this might work a little better:
5 Plague Marines: 2 Plasma Guns (145)
7 Plague Marines: 2 Flamers, Plague Champion, Power Sword (201)
7 Plague Marines: 2 Meltaguns, Plague Champion, Power Sword (211)
Now the Plasma Gun squad can hold a home objective, or hold out in some cover and just provide a bit of fire support for the troops, since the Obliterators will likely be focusing on vehicles I think a little extra fire support will be useful.
The other 2 squads can advance or hold for a counter charge. I assume they can still fill the same role you originally intended for them. There is enough points left for 1 Power Fist, but personally I much prefer Power Weapons, so you can spend those extra points elsewhere if you want.
So:
Daemon Prince: Looks fine for 1000pts, obviously Warptime would be good but is a few too many points out of reach, I've left points for a Mark if you like my Plague Marine configuration. This guy will need to get to the enemy fast and just cause some early havoc to take pressure off your other troops and might get some scare tactics happening to if your lucky.
Plague Marines: As I said earlier, or if you wish to use them as you have loaded them, then I think they will still be ok, but without any Power attacks they will be a little unimpressive in combat. I'm also not a big fan of mixing special weapons, mostly just because I've never tried it, but the consensus is that a pair of the same is better. Alternatively you could swap out one squad for a Chaos Marine Squad, which will be a little cheaper, but then again a little weaker too.
Obliterators: Should work fine for AT, I would be inclined to set them up with a nice vantage point with the rest of your army and have them as AT mainly. I wouldn't suggest deepstriking them, as stated earlier they are your only AT for early in the game.
Hope that's helpful.
~ Lord Tyrannicus