What is it that does it for Fenix versus Apple Watch?

Couldn't you argue that there is actually too much data? Do you really actually need it?

"Need" is a relative term. Very few of us even need a fitness watch at all.

But for whatever it's worth, I do use a lot of the data. Do I need to? No, all I need is my health and a pair of running shoes.

Besides, a lot of Fenix buyers aren't just primarily runners. It's an outdoor adventure watch, that's what it's designed for, regardless of what everyone is using it for. For example, for backpacking, the Apple Watch is undeniably a huge step down from the Fenix, in almost every way.

so for someone who hikes often would immediately realize that difference after a couple hikes with both watches?

Would be pretty easy to notice the difference I think, after a 10 hour hike one of them would have 90% battery left, and the other one would have died 2 hours ago

Does anyone only use the fenix for activities and shut off OHR for everyday use? Again I feel like OHR is just not an accurate measuring tool.

For me, (aside from being a data geek so looking all the time to numbers that really i could live without and I know, but... I like them!) One of the reasons is that the Fenix looks and feels like a watch, while the AW looks more like a teckie toy, nice but I see it fit on my niece wrist, not mine (I understand could most probably be my bias, but that's how I see it). I do know I have strange taste but also hate bright amoled displays on watches, makes them - again - look like something else. This I guess since also very much liking the traditional watches, the Fenix feels and looks just right. Additionally, don't like the whole apple ecosystem philosophy of closeness, and an AW is only usable within that. Ultimately... I don't like to bring additional chargers for my yearly 2 weeks vacation 

I have both an apple watch 6 and now Epix 2 [had fenix 6s pro before]. I only use apple watch during the week for closing activity rings as it is easier to use and see. I don't really care for notifications, siri etc as I always have my phone on me or next to me. To me apple watch feels more like a gadget and garmin one a tool. I like to hike and that is the main use for the fenix/epix.
I love seeing the data, ascent/descent, elevation, max elevation...etc and the map. I don't know of an easy way to see those on the apple watch without going through some hoops. Plus, after the hike, I can see everything including the track on the map,  elevation profile etc on garmin connect website. There is no apple website I can go to to see my activities in detail.
I now have tons of hikes on the garmin connect website. If I want I can search for anything based on distance, elevation gain etc to find any old hikes. You can do a lot of reports to analyze the data whichever way you want. There is no equivalent of garmin connect site for apple watch which is a huge thing for me.

Plus like others have said, battery life. 

not trying to be an ass, but what is the intended use for this data? How is collecting it useful? Seems just a way to hoard data with no real purpose beside the one off situation where you would look back at it for whatever reason?

Ahh...yet another case of the well-known, almost incurable Apple blindness.

Welcome to 2022, your smartwatch will now last for weeks as opposed to Apple's "the same 18-hour battery life" with which all of their Apple Watch presentations end :)

As for the "too much data", the purpose of it is to help you improve. The difference is that Garmin helps you improve while the Apple Watch records what you already know for the purpose of showing off your achievements on social media.

People only use like 5% of Garmin's data, but each person uses a different 5%.

ok I'l bite too 

In my case, those are like a collection of hikes, I can go back to and refer if I do that again etc.. I can also share the page for anyone who wants to do the hike and wants to know the detials. Also, I can do any of those in the 'navigate' course mode in the watch with ETA, distance remaining etc...showing..

When I said I love to see the data I was talking about the current data during the activity like current elevation etc..

Also, I use the watch for navigation, or mostly see my ETA back to the trailhead what kind of elevation is there etc..etc..
so when my non-garmin friends ask me what time will we get back, how many more miles etc., I have an answer 

Then after the hike, I can 'share' the activity so they can actually see all the data about the hike like the track on the map and the elevation profile. 

I don't think I can do any of these on apple watch.

Again, you can just do the hike or run in the city without any kind of watch 

Incorrect.  I get 3 days with no activity on a Cellular AW7 SS 47mm.  But you hit the GPS and Cellular, along with Bluetooth for music for 2 hours running and it hits the battery for 50%.   

But I have everything on my wrist.  I don't carry a phone anymore!

FYI, I also own the Epix Gen2 and love it.