The SE is essentially the AW4 body with upgraded SIP and sensors for each iteration forward: SE1 has the S5 SIP and the SE2 has the S8 SIP. If budget is the primary consideration however, I’d say the AW6 is the “sweet spot” in terms of feature set and price for the refurb market in places like backmarket.com.
The “clutch” feature that is missing on the SE models is the Always On Display, since being able to glance at the time from your wrist without needing to raise to wake is a primary function for a wristwatch IMHO and something that annoyed me when it was missing from my older AW2.
I don’t think it’s a “cost saving” measure on Apple’s part, since an LTPO screen is included, but rather a withheld feature to make consumers look to the next model up for the upgrade path.
If it is a hardware restriction however, IMO it’s something they should include in the SE3. The AOD can be manually turned off if the feature annoys you or you can go into low power mode if you are trying to optimize battery so there’s no reason to not include that feature.
Infograph is easily the best for complication density, unless you are on an Ultra, then you also have the Wayfinder and Modular Ultra Watch faces, which I kind of wish Apple included (minus the ultra only features) in the other Apple watches that can run the latest Watch OS.