Well, I dunno myself which suit I like the most. From time to time I switch up and think differently on things, after liking one design for so-long, I get bored and like the other I guess.
So on that....of course, the Varia-orange is probably my favorite, and it's the one she's known best for......and for that reason, I get tired of it. The classic standard-issue(standard issue, it was Chozo made!) suit is occasionally also my favorite just because that's the real suit, and honestly it doesn't look all that bad(uhm....I don't see it in your list...

).
Dark Suit DOES look ugly. But because of the pure 'mechanical' look to it, I almost like it. It just reminds me how much I dislike MP2 however.
Light suit is kind of good, but looks like it was made by Nike. I also think it looks *nothing* like a Metroid design, so it kind of irritates me.
I actually somewhat like PED....but yah, not a WHOLE lot. The scenario really reminds me of Fusion though...she was doing a job for the Federation, should have been paid, but instead she owes her life to their science and ...the whole saving-her-life thing, and has to work for them because of it, and has to get a new suit in the process. It's this sort of weird 'the tables have turned and you now owe us and the suit is on 'rental' so don't get anything on it' sort of thing.
It was cool to see it gradually corrupt though. And the way she looked after defeating each Seed, she just looked calm, cold, and heartless, and with each corrupted, resembled and looked more and more like Dark Samus. If you ask me, she was being 'trained' to become a suitable(keh, no, didn't mean that pun) host for DS, but who knows.
Phazon Suit was cool. Actually PS was probably the 'original' Dark Samus if you think about it.....eh, not gonna debate that.
But anyway. I typically just like the Classic and the Varia myself...the rest are cool, but a lot of times they just seem out of place....even Gravity Suit, but mostly cuz I don't really care for the colors...I just never got used to it.
...hm. Makes me wish I still had Fusion and/or Zero Mission ... I took them back tho'.
OH, but yes-- definately a fan of Metroid. Honestly Metroid is like 'my Zelda', and for that reason, I wish they would have put in a little more effort for MP3, odd as that sounds...it still had a lot of quirks and things missing that bothered me, but anyway.