Which watch model and whether to get cellular or not depends a lot on your situation, phone patterns, and how you want to use the watch.
There are a lot of good threads around here, chockfull of information, including at least one I started when I was in your situation and trying to figure out how the watch worked.
From what I’ve experienced with my Apple Watch, and read from others, the following applies:
1. A cellular-equipped Apple watch will automatically do SOS Emergency calling — e.g., when you fall. That feature alone is easily worth $100 extra!
2. You don't need to have turned on cell service on the watch for that, nor have your phone with you or anywhere close.
3. You also don't need a cell plan to gain that advantage.
4. You don't even need to have your phone around for most watch functions!
5. The question about WiFi is a good one. Leaving it on drains the watch's battery big time vs. leaving it off. I get 3-4 days use from AW 7 that way. Of course, turning cellular on is an even bigger drain.
6. Toggling Bluetooth is a hassle, having to do a deep dive through menus. We just leave it off, even though people claim it's not much of battery drain.
7. You don't need BT on — or the iPhone nearby — to have a virtually fully functional watch, whether it's a cellular one or not. You won't get notifications or music streaming from your phone (or the aether!) in that situation — naturally — but you will get just about everything else!
Was there something in particular you wanted to do with the watch? If you offer your possible uses or hoped-for scenarios, we can give you specific advice.