In my opinion, Tizen is better than Android Wear for smartwatches. I mean, even after like 2 years, you cannot make a customized list of pre-defined reply messages in Android Wear, which should have been basic functionality from day one.
Hardware-wise, the LG Watch Urbane 2nd Edition is way above the Gear S3. The screen has like 25% more area and is closer to the top glass surface. Battery on the LG has 570 mAh and lasts 4 days with GSM functionality ON. There really is no contest.