Price
Let's get this one out of the way first. The SE 3 is the least expensive Apple Watch, priced from $249 for the 40mm GPS-only model to $329 for the 44mm cellular model. The standard, mid-tier Apple Watch Series 11 starts at $399 for the 42mm aluminum GPS model, costs $529 for the 46mm aluminum model with cell connectivity, and goes up to $699 and $749 for the 42mm and 46mm titanium versions (that are only available with cellular). Titanium seems to really make the difference in price, because the Apple Watch Ultra 3 is just $50 more than the most expensive Series 11 version; it's only available with a 49mm titanium case and cellular connectivity, and is $799 with the Alpine Loop, Trail Loop, or Ocean Band bands, or $899 with the Titanium Milanese Loop.
Winner: SE 3 (It's the cheapest)
Size
The SE 3 comes in 40mm or 44mm versions, with both models measuring just 10.7mm thick. The smaller SE 3 is the lightest of the Apple Watches at just under 27 grams, while the 44mm SE 3 is 33 grams. The Series 11 has 42mm and 46mm variants, and it's the only watch of the three that comes in under 10mm thick (9.7mm). The 42mm Series 11 is also quite light at approximately 30 grams with an aluminum case and 35 grams in titanium. The 46mm Series 11 weighs about 37 grams in aluminum and 43 grams in titanium. The Ultra 3, as always, is the biggest at 49mm and 12mm thick, and is by far the heaviest at about 62 grams.
Winner: Series 11 (It's the most svelte, but with all watches, it depends on what the right size is for you)
Display
All three watches now have always-on displays, a first for the Apple Watch SE line and arguably the SE 3's biggest upgrade. Its LTPO OLED screen is still a few steps behind the Series 11 and Ultra 3's LTPO3 OLEDs, with the smallest measurements (759mm square millimeters for the 40mm, 977mm^2 for the 44mm) and the lowest light output (up to 1,000 nits peak brightness). The Series 11 display measures 989mm^2 for the 42mm model and 1,220mm^2 for the 46mm model, and has a 2,000-nit peak brightness. The Ultra 3 has what Apple calls its biggest smartwatch display yet, at 1,245mm^2, and up to 3,000 nits.
Winner: Ultra 3 (Brighter, and just a hair larger)
Processor
The same Apple S10 chip drives the SE 3, Series 11, and Ultra 3.
Winner: Tie, all three (S10s for everyone!)
Connectivity
For basic connection options, every Apple Watch has Bluetooth 5.3, Wi-Fi 4 (802.11n), and L1 GPS (GLONASS, Galileo, and QZSS) standard. If you want cellular on your smartwatch, 5G is now available for the first time, as well as the already established LTE. The SE 3 makes some compromises, with 2.4GHz-only Wi-Fi instead of dual-band like on the other models, and it lacks their ultra-wideband for precise location tracking and BeiDou GPS compatibility as well. The Ultra 3, as always, has the beefiest wireless toolkit. It now has satellite connectivity for Emergency SOS, Messages, and Find My, and like the Ultra 2 also features L5 GPS on top of the less accurate L1 GPS.
Winner: Ultra 3 (Satellite communication on top of everything else)
Fitness and Health
Blood oxygen monitoring is finally back on the Apple Watch in the US after over a year of being absent! It's available on the Series 11 and Ultra 3, which also get the new ability to detect signs of chronic high blood pressure (hypertension). The SE 3 has heart rate monitoring with irregular rhythm notifications, sleep tracking with sleep apnea detection, and temperature sensing, which is still a pretty good collection of health tools for a budget-priced smartwatch. The Series 11 and Ultra 3 have all of those features, plus the aforementioned blood oxygen sensor and hypertension notifications, and an ECG app.
Winner: Tie, Series 11 and Ultra 3 (Blood oxygen tracking has returned, and hypertension monitoring is now available)
Durability
Water resistance to 50 meters is about all the ruggedness you'll get with the Apple Watch SE 3. Stepping up to the Series 11 adds IP6X dust resistance, and the aluminum version's glass is twice as scratch-resistant as the aluminum Series 10 (the titanium Series 11 and Ultra 3 both use even tougher sapphire crystal). The Ultra 3, again, is the closest you'll get to bulletproof, with water resistance up to 100 meters, a depth rating for up to 40 meters, and an EN13319 dive certification. It's also been tested for resilience against altitude, high temperature, low temperature, temperature shock, humidity, immersion, freeze/thaw, shock, and vibration under MIL-STD 810H procedures.
Winner: Ultra 3 (It's by far the most rugged)
Battery Life
Apple says the Ultra 3 can last up to 42 hours on a charge with normal use, while the Series 11 and SE 3 can last up to 24 and 18 hours, respectively. Apple has been low-balling those numbers for a while, and that's the case with this generation, too: The Series 11 lasted 43 hours, the SE 3 lasted 46 hours, and the Ultra 3 lasted 63 hours. The Ultra 3 wins, but all three have admirable longevity for smartwatches.
Winner: Ultra 3 (It'll just keep going)