I don’t know what an iwatch is.....you mean AppleWatch?
We have a Series 2 and Series 3 Apple Watch In Aluminium, in 42mm and 38mm non cellular, GPS only.
The 42mm has the sport band, that is fantastic, the 38mm has the sport loop that is very comfortable. (You can get cheap knockoff straps on amazon)
At the time of purchase of the S3, no cell provider in MB supported cellular for the watch. But, phone calls on the gps only watches are still fantastic.
Everything about the S3 is better in-terms of speed. Siri is fantastic.
Both watches can go a few days between charges, unless you do a lot of talking.
IMHO, get the S3 over the 2, definitely over the 1.
Just get the Aluminium, unless you really like the feel of the SS.
Try on some different straps. I like them all, but I use the sport band.
I only take my watch off to charge (only takes an hour or so) so it’s been through a lot, and still looks new, nearly 2 years later with no protection.
Solid units.