Well, here's my two cents:
-If you're concerned about how the army is going to look and you're not such a great painter (not that there's ANYTHING wrong with that), Skaven would definitely be a better choice. Because they are supposed to look messy, trashy, plague-ridden, etc., I think that the Skaven actually look better when painted by less-skilled artists. Colin Grayson's Skaven army that was featured in WD a few months ago is a brilliant example; messy, and it looks great because of it. WoC- not so much. Lots of armour, lots of weapons, lots of Chaos icons, etc. Even Nurgle has units like knights, and if they look messy, it will detract from the whole army's appearance.
-Playing 1000 pt games, you are looking at unit sizes that can still support up to 30-40 clanrats per unit, but probably only 10-15 WoC per unit if you were to go that route. Less painting, but less guys to do interesting things on the battlefield, too.
-You'll never find a monetary deal for WoC like you will the Skaven army in Island of Blood. You're going to get your 1000 pts, plus all the other loot, for the same amount of money you'd spend on a few boxes of warriors. So, if you still need an 8th ed rulebook, or if you have any interest in maybe also getting 1000 pts of HE (or trading them in order to get a monstrous Skaven horde), then that's the route I'd take in your shoes.
Good luck either way.