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I have had several Garmin products in the past. Some are good, some are bad.
The pros: Garmin is the de facto GPS so a lot of gps data is geared toward their file format.
Middle of the road: Hit and miss on reliability/durability. Customer service can also be hit/miss.
Cons.: Expensive.
For me, a major factor is the battery use. Some units (Montana) will go thru three AA batteries per riding day or day and half. Others (62) can last a few days on two batteries. Batteries are heavy so even though I use a dynamo hub, I still carry several batteries since I may not always recharge quick enough or will be charging something else like my phone. If you do not use a dynamo hub, you have to carry lots of batteries as you do not want to buy them at some back-water store where they have been sitting for 6 years and are half dead. Thus, you have to have a Walmart type store in order to buy new ones and the stores can be a week apart at times, thus 3 batteries a day x 7 days equals a lot of weight.
I currently prefer the Model 62 as it holds a fair number of waypoints and track points in addition to routes and tracks. The screen is not very big compared to the Montana but the battery use is way less.
The Montana is a battery hog. It is relegated to my car trips where I plug into the cigarette lighter. It has a nice large screen and is a touch screen. It is a smidgen easier to use than the 62 but the buttons have literally melted due to sunscreen lotion getting on them. It may have been just really crap material but the only thing that could have done it otherwise is the sunscreen.
The Extrex is not bad but the sound for navigation cues is fairly low.
Considerations: Are you going to ALWAYS have a cell signal? If so, use your cell phone. Assuming your cell phone has a GPS built in, it can probably work even without a cell signal in the airplane mode.
Does your significant other want to track where you are going at all times? If so, AND you have a cell signal at all times, you can use your phone and with an app that tracks your location. If you are going where there is no cell signal, then consider Garmin's InReach/GPS combo unit. I have the stand alone InReach also. It is very good but a bit pricey for the subscription plans. However, I sometimes do remote touring (remote forests, Alaska, etc.) where there is no signal and she wants to be able to know where I am in case the bears eat me (doesn't matter that by the time help arrived, I will have probably been eaten, digested, and pooped out). At least she will recover the bike. It is very very accurate, within 10 feet I would guess.
Finally, do you even need a gps device (only you can decide)? If you are dealing with lots of turns on say the Atlantic Coast Route, then it really does help. If you are on the Western Express, probably not as there just aren't very many turns to get lost. For decades, everyone got by fine with just the maps and odometer (bike computer now) and maybe a compass. They are nice but usually not needed.
Hope this helps. Tailwinds, John