None of the data the glasses display, except for power, are of any real value to the degree that you need to see them constantly. Heartrate is pretty worthless, and I actually often make a point of NOT looking at distance, like on a longer ride - it can make the ride feel like it's dragging out. Especially with an out-in-front computer mount which are very common these days, glancing down at your bike computer really isn't much of a hassle at all.
Consider spending money on things that will make you more likely to ride, such as clothing for different weather conditions - or if by cycling you mean "for transportation", things that will increase the utility of your bike.
If you want really good mapping and routing, check out the Hammerhead Karoo head units, which run Android. Top-notch routing. The garmins are...OK. Garmin's definitely been far too cozy (little serious competition.)
RE Garmin — my first computer was a xoss g+, which was pretty good. And I recently switched to garmin edge 530 because I'm planning to get a power meter soon and I have to say I'm not a big fan — screen quality and navigation are kinda crapy for the amount of money they ask for it.
Heart rate, again, I find more useful for training, but in some cases can indicate fatigue that you may not actually feel in the moment.
It’s not really useful for checking while riding though, it’s more along the lines of a data logger. Might be a bit different with a mount for the phone, but I avoid having visible elevtronics while riding.
Also, over the course of a marathon, with my phone GPS, the distance has been up to a mile off. For my last marathon, my watch (w/o Bluetooth on) was only 0.1 miles off.
I’m not sure how much of a problem this is for cycling, given the differences in speed and distance, but for running, it can be quite the problem.
Note: I have the cellular Apple Watch, but I don’t think it uses A-GPS.
The phone and iPad will generally show the path I take relatively accurately, including side of the road, and In some cases lane positioning.
The few times I’ve used the watch on its own(for walks), it’s been significantly worse, with paths going off through nearby houses. Either the frequency of locations is lower, or the accuracy is worse.
I probably wouldn’t get another watch after living with one for a few months. The heart rate is interesting, the apple pay is nice but not that much better than the phone, and sleep tracking is iffy.
This may change if I can get good haptic way finding working, but that’s going to be a Project.
I didn’t really notice the difference and accepted the low GPS quality from my phone until I got the newer watch with the cellular chip. Then I could go for runs with music and GPS without my phone. The difference was amazing. The newer generations of watch are much better. And cellular was better then GPS only, ironically. YMMV - I think a lot depends on where you are and the towers that are nearby.
That said — I’ve also considered just flipping to a Garmin watch. The battery life in my Apple watch isn’t enough to get me through a marathon, tracking GPS while also listening to music (I’m not fast, so ~ 4 hours).
That might explain one of my rides having a spurious "cliff climb" where the altitude went bonkers.
That being said, I lost interest in Strava when they killed the Bluetooth integration with my Wahoo TICKR. That was just another of the incessant reminders of why I can't trust tech companies anymore.