Cowon I-audio S9:
I'm planning on getting the Cowon S9, the 32GB version soon, but its really expensive here in the UK, at £159. I wouldn't try importing if I were you either (if you ever consider it), as its probably more trouble than its worth.
You can get a 16GB model however for £199.
The size shouldn't be a problem, as its just as big as the Touch (plus slightly cheaper at most retailers for 32GB), but maybe slightly thicker, but as its curved, it doesn't seem to make much difference.
This has been considered the best sounding player around, and also happens to have one of the best screens in a portable media player, a AMOLED screen. I haven't seen it in real life, but I'm sure it'd look spectacular if words are to be taken as truth. It plays a wide range of video formats also of course, and ones it won't play natively can be converted using the software provided.
It also has customisable UI's which I could see messing about with an awful lot; downloading new ones, etc.
It also now offers gapless in most files, FLAC/OGG V/MP3 (Lame codec) in the latest update, etc so if you have a album thats meant to have no gaps, it won't have gaps + like every Cowon player, has folder support, so you don't need to mess with ID3 tags (preferable for me)
It offers no card slot for extra memory though like the D2+ which is worth considering.
Cowon I-audio D2+:
Another player that you may consider is the Cowon Iaudio D2+. It comes with up to 16GB memory, BUT, supports SDHC for unlimited storage capacities (32GB cards for example)
Sound of course being a Cowon is meant to be top notch, but from what I've read, isn't as warm sounding as the S9 but still as detailed as you can get, but still better I'd imagine than most of whats out there.
It plays video like the S9 but the screen is a lot smaller, and is an LCD, and like the S9, its a touch screen, but using a different type of touch screen; a resistance, rather than a capacitive one.
Of course, it won't offer gapless, like the S9 within a firmware upgrade, because it'd offer more competition for the S9. But for me, since its the cheapest option, it may be the most sensible, as it'd probably do all I want; but I'm still not sure on it. I think it may be due to the fact that the S9 is meant to have the better sound, but for the price, and still being a Cowon...
Don't get the D2 confused with the D2+ by the way, as the D2 uses different materials (its better looking actually), but doesn't have support for BBE+ but instead, the older BBE (don't know how much difference there is in sound quality). My old M3+ had BBE only, and I was very happy with it.
Battery on both compared:
Battery life on both devices are also top notch, hitting the 50-60 hours mark, with around 10-11 hours video (using test settings).
I hardly ever had to charge my M3+.
Both offer BBE+ sound settings which make the players sound truely amazing. I had a I-audio M3+ (it died) before I got my Creative Zen Vision M, and I swear, I missed the sound on the Cowon while having the Zen (hard drive has now died)
The bass with Mac3bass is spectacular.
Deep, but very tight, especially on my PX-100's which are also amazing headphones for the money.
So, if you want the best, go for the best.
I'm going to be ordering my S9 soon, but the D2+ is still rather tempting, if not just for the unlimited memory for FLAC, and the fact that its a whole lot cheaper.
I've rounded up the others you've mentioned below, trying not to be critical, but based on me:
I've questioned the Samsung myself, as its going to be £150 for 32GB memory!!! But after many reviews of the sound not being as good as the Cowon (and knowing thats why I'm buying a player in the first place), I have to pass, but if you liked the sound on the Samsung, it may be fine for you, and will offer a lot more than your old model + plays all the sound files you specified.
I'm not sure what that video format is though I'm afraid to know if it'd play that, but conversion should be possible.
The Ipod to me though is a no no. Its far too expensive for me to even consider it as a choice (a lot more expensive than the S9 for 32GB in most retailers), with the sound on I-pods never being great to my ears even with good headphones.
There is a way around the software issue at least, where you don't have to use I-Tunes by the way, but to me would still be far too limiting of a device, even if it does have WI-FI built in.
Sound formats are also non-negotiable for such a device with less to offer everywhere else.
They could do something about the sound, but they don't. Most people wouldn't care.
I for one want a great sounding MP3 player, even if its not one that everyone looks at going "ooooooooOoOo". If it does what its meant to, and sounds great because of it, then thats good enough for me.
Sound will most likely be better than the Samsung on the new Sony, and will beat the I-Pod by far if the other players are to go by, but apparently doesn't match the S9, with sound features turned on at least.
The fact it doesn't support open source files though is a turn off for me.