They are all pretty good for their individual program types. The only real problem is the repetition. This isn't quite as bad as it used to be. It's also exaggerated because of the lack of HD channels. ALL cable/sat channels are pretty darn repetitive. The difference is, when you've got a new HDTV, you really want to watch an HD program, so you just look at the HD channels and you notice how repetative they are. When you're looking at 200 channels instead of 20, the repetition doesn't stand out.
The main thing to look at is, are you interested in the channel topics/themes? Monsters is one of their best channels, but if you don't like horror movies, it doesn't matter. Same for Kung Fu.
FilmFest is one of the few "general interest" channels. The quality is good- both picture and programming- and it's not overly repetitive (unlike the channel it replaced-"The Majestic".) However, World Cinema has been a bit of a disappointment for me- I just haven't seen much I've been interested in. I suspect if you are a hardcore foriegn film fan, you might like it better. I personally fall in the middle on foreign films- I certainly enjoy a good one, but I'm not the snob type who watches everything that comes along in another language. I think the problem is, they don't show particularly well known films, so I don't know what's good and what's not and I don't have time to experiement.
The only other movie channel is Family Room- it's lacking a little in good movies, although some of the old TV programming is a kick (Flipper, Thunderbirds!)
Rave is an excellent music channel, but again, they need more programming. Plenty of variety, although it skews a little older- you're not going to see Disturbed on there.
WorldSport is good for Soccer fans, or displaced Canadians, but not much else.
Rush is the "extreme sport" channel, but it does have some stuff of general interest, if only for beautiful scenery.
Ultra is mainly the "fashion channel", but they do have some programming on fine food.
I found Gallery interesting too, but surprisingly, Treasure has some good stuff as well.
HD News is good quality, but obviously you're not going to turn there first for breaking news. It's a good place to catch up on world events for 10 minutes or so, and has probably replaced Headline News for that purpose in my house.
Gameplay is strangely fascinating in tiny doses, but basically only of interest to hardcore gamers. Animania is fairly useless to me (and I love cartoons), but I might feel different if I had a 5 year old. (The Toons LOOK great though.)
And that just leaves Equator- a decent alternative if you don't like what's on Discovery.
Really, they're all good, not great. Good picture quality, not great...good programming, not great. If you aren't interested in any of the special interests represented, you might not care much,as there are only 2 or 3 "general interest" channels.