[Android General] eksasol:
I want to share some experiences I have with the Galaxy S devices. It's a bit late to post this perhaps, old news even, since Galaxy S is no longer new and is only single core, but there are a few features that give these phones excellent value, especially for those who want to buy a phone out of contract and don't want to pay too much:

-Used ones can go for around $150, less if lucky

-Very easy and cheap to unlock

-Generally good battery life that can last whole day

-AMOLED screen, viewable under sunlight

-Good build quality (Gorilla glass)

-5MP camera takes decent pictures and 720p video with adequate lighting (most variants don't have LED flash)

-Decent graphic card (200 MHz PowerVR SGX 540) can handle all recent 3D games (ie. RipTide & Asphalt 6)

-Easy to root and has great developing community (CyanogenMod supports)

-Support "ODIN", easy flashing factory images in Download mode, making them very difficult to brick

-Used Wolfson DAC which yields great audio quality, which is not featured in the S II and Note

The Galaxy S variants I've owned are: S 4G (T-Mobile), Vibrant (T-Mobile), Captivate (ATT), Nexus S (T-Mobile). I have unlocked, rooted and flash roms on all of them. I also had the Galaxy SII and Note (International).

Overall impressions:

Nexus S: This has to be the most desired of the lot, best screen, best performance, latest OTA update directly from Google and has lots of developers for it. It has LED flash which most of the other variants don't. It also support Near Field Communications. However, it is not my favorite version.

Downfalls:

-no microSD card slot, only 16GB internal

-due to its curved shape, with a case included it can feel bulkier than other Galaxy S variants with flat body

Vibrant: This is my favorite of the lot, simply because it works on both T-Mo and ATT 3G, this is rare for an Android device this cheap. It's not pentaband however (doesn't support ATT 850mhz). It has internal 16GB storage and microSD expansion. Cyanogen support and lots of custom roms.

Downfalls:

-Needs GPS fix patch for custom roms, GPS lock time is a few seconds slower and less precise than other variants.

-(correct me if I'm wrong) It doesn't yet have the official T-Mobile 'WiFi Calling' app that the Galaxy S 4G has, but there is works on a custom version. IMO, you can just use GrooVe IP instead.

-No front face camera (I think there is a rare few Vibrants that does have it)

Captivate (ATT version): This device is the nicest looking Galaxy S I think, due to its slanted design. It feels just a tiny bit slower than the rest to me, I could be wrong, but it just feels that way. Like the Vibrant, it has Cyanogen supports and lots of developers, 16GB internal storage + microSD expansion. No front face camera unlike the Captivate Glide and Sprint's Epic 4G though.

Galaxy S 4G: There is a mix of good and bad for this device. It has good data speed (10Mbps+) as long as you live in a good T-Mobile coverage area, which also results in good tethering experience. It includes the app "WiFi Calling" so you won't use up minutes. Front face camera included.

Downfall:

-Lacks internal storage for users, needs to have microSD card. That also results in apps installed to microSD card by default, this can interfere with functions of some apps. Not sure if stock roms can do this, but you can always manually move the apps to internal storage, sometimes its a must for apps to autostart and for some app's widgets to show up in the widgets selection menu.

-Much less developers available, no CyanogenMod support. Only until now there is some work on porting CM7. With that said, the available Valhalla rom makes this device blazing fast, but also no longer worked on by its original developers.

More info:

Performance:

I'm not basing so much on synthetic benchmarks, but regular usage. The Nexus S seems the quickest and I achieved ~2500points for Quadrant. Aside from that all of devices I've used are on par, they all can play 3D games smoothly. They are all kind of slow with stock rom, but once you put in CyanogenMod7 or 9, they're blazing. In fact, I feel these devices with CM7 are more responsive than stock Galaxy S II and Note (in term of general navigation, of course newer phones are faster overall).

The Vibrant gets low Quadrant score, around 1500, but it seems just as fast as other ones. I feel the Captivate is slowest of the lots, but the difference is so small it doesn't matter. The key here is to flash custom roms.

Data speed:

The Vibrant is the best in term of value, it's not fast, but supports both 1700 and 1900 bands, so can work on both T-Mobile and ATT 3G networks, it does not support the newer ATT 850 band however.

S 4G

: theoretical 21Mbps, I've achieved over 10Mbps

Vibrant

: can get up to 6Mbps with good signal, generally stays around 2-3Mbps

Nexus S

: theoretical 7.2Mbps, about same with Vibrant

Captivate

: theoretical 7.2Mbps, but ATT HSPA network is generally slower than T-Mobile imo, it all depends on the area of coverage though

Galaxy S II (T-Mo)

: theoretical 42Mbps, I've achieved 24Mbps

Also note that with T-Mobile devices, I've been able to tether freely. I know that some people with the $79.99 plans have had text message from T-Mobile that warns tethering is not included with their plan.

GPS location fix:

These devices work pretty well as GPS navigator since their AMOLED screen remains viewable outdoor. They all generally takes around 6-10 secs to get a fix outdoor. The Captivate and Vibrant using custom roms required GPS fix patches. I have the most trouble getting location fix with the Vibrant which can take longer than 10 seconds. I've lost GPS signal on the highway with the S 4G with dark clouds overhead. These devices while does a good job, are not reliable as devices that include both GPS and GLONASS support, such as XPeria variants and the Galaxy Note, these can get really fast location fix and rarely lose signal.

Screen: The Nexus S has best screen quality than the rest of American carrier-locked variants, which all has 'blue tint' to them, although just as crisp details. However, if you have CyanogenMod9 installed, you can change the color temperature of the devices to warmer to match the Nexus S. There are no CM9 for the S 4G currently however.

Final:

If I have a final say about the Galaxy S model, is simply that it has Wolfson DAC, that is a big deal for audiophiles like me. The SII and Note just doesn't sound as good, regardless if they are more powerful devices. With that said, I recently got an XPeria Play which also has some excellent quality too, so XPeria devices might worth looking at if audio fidelity is your concerns.