I haven't used a Bolt but a friend has a Wahoo Elemnt and really likes it. Myself, and two of my main cycling buddies have Garmin Edge 820 (regular, not the explorer) computers. I personally have owned and extensively used Edge 500, 510, 520, and now 820, and the 820 is the best one I've used yet. Stable, functional, and generally a nice unit. Truth is, you probably won't go wrong with either one.

Having said that, I'd probably nudge you gently toward the Garmin since you've been using the 920 so you're already inside the Garmin "ecosystem." If you get a Bolt and then find your 920 you'll then have two devices that utilize different platforms. Maybe not a big deal, but why add complication if you don't need it?

I've gone through the 705, 800, 810 and i'm now on a 520 (bought 2 weeks before the 820 was launched, or i'd have had the 820!) All round, the 520's probably the best so far - though I miss the touchscreen of the 800 series and the better navigation options. 705 and the 800 were probably the most "stable" (and both still work, though their battery life is now such that anything over a 40 mile trip is touch and go if all of it will record), 810 was a pile of crap from day one, every update broke something else, the navigation (turn by turn) pretty much never worked properly, and the whole thing would "hang" if you were in areas with complex road systems - it felt like the software was asking too much of the internal hardware's processor - a bit like trying to run Windows 10 on a machine that originally shipped with windows 95...

Can't comment on the competition - I've stayed with Garmin, because despite the occasional flaw, they have pretty much recorded every ride I've made since 2007... Thinking back, I think i've actually lost 2 rides, and had 3 "truncated" through battery fails. Sure, I had to "fix" half a dozen during the 3 months I had a 810, but that was a second hand unit that I'd been given. call that 11 problems - out of 1897 recordings (as per veloviewer this morning), and over 64,600km of rides taking 2926 hours plus change... I can live with a 0.00579% error rate.