Not all required rooting. Have you hold and try a Nexus S before. Before its look great on paper or picture.
Once you hold it feel flimsy and cheap. Incredible S does have very good build and specs compare to Nexus.
2.2 is actually good enough for use and like my self I don't even bothered with root on all of my android. Arc, X10, X8 and Galaxy 7.
Getting a Huawei X5 soon and also not planning to root or custom room as its good enough.

nexus s for the fastest devices to get official os updates, superb wide community...

why nid to go ebay when theres some shop oledi selling around that price & no nid wait shipping o.O

Best is determine what you want and need.
1. Do you need custom rom?
2. What spec do you need.
3. What build quality, design, feeling that you need

When I buy a phone I will consider these things.

1. Design. Not your typical pda look phone. Should be a bit out of average. Phone is also a fashion statement.
Don't want to buy a phone that quite similar design with few models.

2. Specification. Decent enough for all the day to day use. Not lagging and not giving me issue while using it.

3. All rounder. HDMI for video player and lcd connection. Install moboplayer in your android and you can turn ypu phone into a decent video player on the go.
Take picture or video and play it on the tv directly. Or play movies and mtv.

Good picture and video as I don't have to bring my camera all the times and you never know when do you need to take decent pictures.

Good GPS device as that are times when you can use while lost or unsure to find your way. Its very useful features.

4. Easy typing and decent browsing. That's why again and again I keep telling new users 4.2 and above its a decent size for android.
The phone is not too big but easy enough for qwerty typing and web browsing. I have a 3", 3.2", 4" and 4.2" android phone.
Even 4" is not big enough and I love my 4.2" Xperia Arc

5. Accessories. Most important is a good high quality hardcase or leather pouch. I don't think Nexus has any except those cheap softcase.
You can find but a bit frustrating compared to the popular model. I got a decent hardcase and never take out my arc case any more.

So if I were you. I may take IS but problem is no HDMI. why not save and get apset of Arc?
Desire and nexus are old models whereby there are many new decent model out now and more is coming.
Judging from your budget I can set you able to get a Arc. I have persuaded a few moto android user, iphone4 users, dell streak users, and desire user to switch to Arc. They are very happy with the choice they made.

My recommendation is go out to a big shopping complex like lowyat, BB, mines and try out these phones. Hold them try them and you know which one you like.
But do bring a internet access to check their specs, accessories given and also price as normally these phone shop will charge quite expensive.
Galaxy S is an old design. Good is accessories not hard to find especially hardcase and softjacket.
Nexus is limited. So far I found 1 pouch and 1 softjacket.
Desire S is quite new but I am seeing its a popular product and accessories getting more and more.
Don't recommend vibrant, not officially release in malaysia and issue with accessories later.
Frustrating when you go phone shop and no casing for your phone but there is a tons of iphone and blackberry.

Worst come to worst save a bit more and get a better phone. I assume your budget around 1.5K.
So top up 250 can get Optimuz 2X, Arc AP and a lot more.

Cons. Single core processor. For some RAM is not sufficient but both is fine for my day to day use.
Best no2 phone in tech radar after SGS2. After using so many android I can say I am very happy with it. 

From the way I abuse it now. I think its good enough for few years.
I am planning to keep this one long. I predict in 2 years dual core will be a main stream standard. In 2 years can sell this and get dual core.
Note that a phone is still a phone. Actually we can still use our symbian s60 fine now or 3gs. But we tend to change to stuff prettier and faster.

When buying the Arc, I was holding Nexus S, Incredible S and Optimus 2x. And you know what I choose.
Just try out and do bring enough cash 

was thinking of getting a mid range phone. now my choice is btw huawei u8800 ideos x5 vs samsung i9003 galaxy sl.
x5 seem to be a good choice as it's around 850 and hv 3.8" screen with flash support.
but galaxy sl is more expensive at around 1.3k but better processor, screen size, gorilla glass, etc..
by looking at price, x5 seem to be a good choice. anyone can comment more on this? thanks.

Best in technology and so so in design SGS.
Great in design and camera, video and super slim and sleek Arc.
Of course I will vote for Arc. But later I also itchy buy SGS2 for second phone.

  may i know the ori set all shop come with the accessories u mention above?