Cowons

You've left out the S9 and upcoming J3 from your list,................

The D2 has some buttons..like the volume up and down :P It's mostly touch screen so you can operate in the dark when you touch the screen and it turns on :P If you change the flash skin to something better you can easily control next/previous/pause song when not looking but with the stock stuff the navigation isn't as easy.

I would pick the i9 because of it's slimmer design mostly. If it's portable I want to be able to easily stick in and out of my pocket without worrying about messing up the screen.

D2+ has the expandability of an sdHC card, the i9 doesn't.

i was surprised at how tiny the d2+ is. it looks much bigger in pictures/videos online. it's slightly thicker than my 20gb 4th generation ipod, so you have an idea......dude just buy it, it sounds freaking amazing.

the interface kind of sucks on the d2+ too but there are a lot of skins/themes at iaudiophile.net and i'm happy with the one i'm using.

I have mine in my pocket at school all day. I wear skinny jeans and it's fine. You should have no problem.
One thing I'll add. I have been using a Cowon leather case for my D2+ and I've only just recently realized how much extra weight and bulk it adds to the player. So if you head down the road of getting a case check out dimensions and weight.

Get the clear case for the D2+, it's much thinner.

The ability to add a SDHC slot and running FLAC files is pretty much a winner in my book. I had the clear case and it worked pretty well. It didn't add much bulk and protected the D2 very well. The D2 is much smaller than it looks in pics and I was surprised how small it was when I got mine.

Like the others have said, the D2+ is pretty small. The controls/interface are a bit strange, but it works.

More than likely the i9 will improve with future firmware... patience! On the other hand, the D2+ flash interface is much more customizable. Perhaps you could try both, return whichever you don't prefer.

I have an i9. I don't know how good the D2 is, but the i9 sounds amazing. It's small, slim and there's a bunch of fun ways of playing with EQ and BBE effects. It also has very similar sound as the S9. However I had a hard time to synchronize my huge playlists, and (maybe it's just my problem) the hold and volume buttons lie on the same parallel positions, so I sometimes accidentally press the hold button instead of the volume from outside my jean's pocket.

the weak point of the I9 is its battery, the J9, if the 32GB model came out would be my choice, 32gb MicroSD cards are still too expencive, so i would rather get the 32GB S9 directly and not have to deal with the card, but if you could push it to 48gb and even to 64GB when 32gb microSD´s become resonably priced, the J3 might be worth it,