Yeah, ipod is possibly best for ease of use, and it is one of the most compact. But it also has the worst sound quality (there was a study on cnet), and probably the worst battery life, and the fewest extra features. And it is more expensive than most comparable mp3 players.
From what I've read, probably the best choice is the Creative Zen Vision:M - see the above post.
The best alternate choices are the Cowon Iaudio:X5 or the Toshiba Gigabeat S.
I have the Iaudio X5. It's interface is a little clunkier (it uses a tiny joystick to navigate, rather than a touch sensitive surface), but it still works fine. The biggest drawback for most is that it does not sort by id3 tags, so you have to organize your files yourself. I actually like this, because I can segregate my music into different folders as I like and can shuffle all my music within that folder, rather than having to deal with inconsistent id3 tags for my mp3s. Cowon has started implementing id3 sorting on their players, but it is uncertain if they will ever add this onto the X5.
The things I like the most are the fact that it is indeed drag and drop, so I can connect to any computer, drag files onto my X5, and immediately play them. No need for 3rd party software. There really are not many other players that can do this now. Maybe iRiver, but it seems they are mostly focusing on small capacity players recently. Anyway, the long battery life is great -35 hours for the extended battery version. The compatibility with so many file formats (wma, mp3, flac, ogg) is great. Sound quality is also one of the best rated.
So overall my Iaudio X5 has been great. The biggest annoyance is that my player has a bug that makes it sometimes stop for no reason when I am playing on random. It may play for hours straight, but eventually it will finish a song and just stop, instead of playing a new song, and I have hit play to start the music up again. I know that other owners have had the same problem, but it is not clear that everyone has this problem. It may be kind of hit or miss. So that is annoying.
Of course, still essentially nothing is gapless like the Rio Carbon was.
If I had to buy a mp3 player now, it would be a toss up between Creative and the Iaudio. The Creative has probably the better interface, but the Iaudio has drag and drop and the ability to organize folders as desired.