For ratings, I just use ANN's suggestions
10 = Masterpiece, exquisite beyond words
9 = Excellent, should be in anyone's collections
8 = Very Good, don't miss it
7 = Good, worth seeing
6 = Decent, I didn't lose my time
5 = So-So, it didn't really grab my attention
4 = Not really good, but not a total waste of time either
3 = Weak, wish I'd done something better with my time
2 = Bad, really not recommended
1 = Awful, avoid at all costs
0 = Worst ever, maybe useful as a sadistic torture device
Those descriptions are easy enough for me to understand. Basically, if I finish watching an anime, it's going to get at least a 5. If I start watching an anime, I've done enough homework that I usually like it and watch it all, but maybe 5-10% of the time I stop partway through and a couple of these I've rated as low as 3/Weak.
As it is, there's 117 I've finished, 3 I'm working on, and 7 I won't finish which I've rated at ANN, and they break down as follows:
10 - 19 so far, including a lot of Miyazaki, Baccano!, Blood+, Cowboy Bebop, Crest of the Stars, Disappearance, Moribito, Mushi-shi, NGE, Samurai Champloo, Welcome to the NHK, 12 Kingdoms, Sound of the Sky, and Xam'd. You may not think these are all 10's, but even if your tastes are much different than mine, I don't think any of you would rate any of these below a 7 or 8.
9 - 53 so far, evidently I think much of what I see "should be in anyone's collections." Includes many greats like Clannad AS, Code Geass, Darker than Black, Eden of the East, FLCL, FMP!, Gantz, Gintama, GTO, ID 1st+4th stages, Lucky Star, MKR 2, Gundam 00, Rurouni Kenshin, Steins;Gate, Trigun, Wangan Midnight, Wolf's Rain, and most of the rest of the Miyazakis. Obviously these are more up for personal interpretation, some of you may rate some of these a 5, but most of you I bet would give most of these at least an 8.
Won't go into the 8's, 7's, and 6's. Last Exile got a 5, as did Argento Soma, Arjuna, and Basilisk from the "will not finish list." Ouran HS and Texhnolyze both earned my contempt and landed my lowest scores yet, Weak 3's, couldn't get in to either of them despite seeing some good points, just didn't like the plots at all, IIRC, though in fairness I didn't get very far into either before quitting, they could get better.