You should avoid Gankutsuou: The Count of Monte Cristo until you watch the other stuff that some of these people are saying is 'good'. Noir is 'good', Gungrave is 'good', etc... But if you decide to watch Gankutsuou: The Count of Monte Cristo, it will likely destroy your desire to watch anything else.

It is that awesome.

RahXephon is still my favourite anime right now, so I wholeheartedly second Wolf Kanno's reccomendation there.

I compiled this list in about 1/2 an hour a few months ago. It's not complete (and I've started/watched a lot of anime since then so it's way out of date), but it should be a pretty good guide. Anything I rated 8 and above are great shows, 9 is an awesome show, 10 is a show that you should make every effort to watch. Juuni Kokki is known as 12 Kingdoms. 7 is a show that is still really good, but ultimately missable. 2x2=Shinobuden is hilarious, start to end, but compared to Azumanga (rated 9) it falls a little short. Etc.

'Course, it's all opinion. Still, Gankutsuou should be on your list. Perhaps you could just pre-empt the other stuff and start there, and work your way down.