If you have Grados, you've got some big shoes to fill. Westone 3, Shure 530s, q-Jays and the Phonak PFEs are high end IEMs. I'm partial to Grados myself. I own an SR80 and I don't think most IEMs can compete with them in terms of sound quality....in a quiet room. However, since IEMs isolate outside noise and most listening of music occurs when there is outside noise, IEMs offer a superior sound quality because they block out distractions.
I own the q-Jays and they sound sweet, however, they're average in terms of sound isolation and I've heard they have sibilance issues. Never heard anything bad about SE530s.
Here are four things that you need to consider:
1. Sound Quality
2. Comfort (this is an important issue therefore, I would suggest buying your phones from an authorized dealer that has generous return policy.)
3 Degree of Noise isolation.
4. Price - most of these will put a hole in your wallet. Unless you're some rich guy in which case you should be partying on your yacht with hot women instead of listening to music on your headphones.