Check sprint coverage is your area before going Helio since Helio runs off the Sprint network.
The ocean is pretty cool, but very buggy. After using two in stores and having a few friends with it I can say that it is impressive, but the amount of crashing is no joke. I used the ones in store for less than 10 minutes before they bogged down and the webpages aren't that great (formatting errors and many pages cause errors). Also the Ocean is not a real smart phone, you can only do 1-2 things at a time and can't do much else while listening to music.
But the speed was very fast (coming from EDGE) and the IMs seen to work well.
EnV is a bit more boring, but I have a friend with one who loves it and it has never crashed in the hour plus I played with it.