We have been using a Garmin 800,outdated  now, for the last 10 years of touring.  It has served  us well. But we are looking  to upgrade  and the Garmin Explore 2 is looking  very good to us.

I think you'll find that pretty much all of them are good at following a route, although some of them are better than others at coping when you deviate from the route. There are a lot of choices, but it probably comes down to something from Garmin, Wahoo or Hammerhead. Screen size and quality of display do vary and I think they are the most important consideration. Also think about how long the battery lasts between charges.

I have had a Garmin Edge 530 for the last four years. I have been very pleased with it but when it's time to replace it I will get something with a touchscreen.

It's worth looking at the reviews of gps devices on YouTube by DC Rainmaker. These are unbiased and comprehensive.

The other crucial thing is that it has a wireless connection to your phone. Older GPSs only have wired connections and these are a huge faff. Being able to ‘beam’ a route straight across is a godsend.

If you are cycling during the colder part of the year consider the useabilty wearing gloves - the reason i stick to devices with real buttons.

"Best" is entirely subjective and very personal.

For anyone considering a dedicated gps unit (and don't forget CT has an app too!) I'd always suggest to have a good think about what you want and how (and where) you will want to use the unit before having a look at what is out there. It can get very confusing!

First of all, a bike gps unit differs from a car one by virtue of the fact that they are best used with a planner. Some will have planning capabilities as well as route recalculation. Generally, route recalculation/planning on the unit is less than optimum - they do not have the computing power. One thing I came across recently was someone was unable to deactivate route recalculation and it was quite frustrating as a better alternative to the  "planned" route was accompanied by a unit going crazy.

Maps are a common area of differentiation - in terms of detail and availability. Depending on your use this may or may not be important. Some people want all the details - I prefer a simple, easy to follow screen. My phone has a bigger screen and better quality maps.

Things like touchscreen/buttons are another difference. As we see above. Personally, I wouldn't touch a touchscreen :-)

Ease of use/dependence on external devices (computer/phone) and ability to personalise may or not be an issue for you. My unit works with my phone so that any and all changes/updates/map changes can be done on the road. 

Always an important issue for me in such an investment is customer service. 

Some people struggle to see displays. 

Personally, I'm not too bothered by battery life. New units have pretty good life and a small powerbank is more than enough to reduce any anxiety. 

Unfortunately, for purely navigation uses, you will probably find yourself paying for more than you will use. There are tonnes of features on my unit that never get used. Like yourself, I use a unit for navigation, but the "recording" feature is something that I have come to adore. Paired with Strava (other options exist) I now have a record of each ride with photos - all at the clicks of a few buttons. Fabulous!

Depending on the type of cycling you do, your needs may be different. For me, simplicity is the key. I don't want a unit that needs to be molly-coddled, just one that works reliably on multi-day (and longer) tours. 

My suggestion, given your needs would be to determine what you want, investigate which option best suits you and seek out a second hand model. Some people are always upgrading their gear and bargains always appear. 

If going new, see if you can actually see one "in the flesh" or where there is a decent returns policy.

Any cycling forum will have many, often heated, debates on different brands and units. Strap on a helmet and get reading for more info! 

Getting a GPS was a fantastic thing for me. Having a unit on my handlebars that could get me out of Dodge was a great confidence booster and let me explore further than I'd have considered before. 

Good luck!

Hi Hermann. Some of the touchscreen devices have retained their buttons, so you do have options if the gloves and the screen don't like each other. I think this is true of most Garmins, but I don't know about other manufacturers.

Hi John. Take a look at the Hammerhead Karoo 2. I have used Garmin and Wahoo, but like you navigation is the most important thing, the Karoo 2 wins based on that requirement. Excellent mapping and clear screen. Works well with cycle.travel. Download .tcx, add it to the Hammerhead dashboard, sync and ride.

My Lezyne Mega XL works very well for me. On a multi day tour, I plan my routes in advance on CT and transfer them to my phone's GPS ROOT app (via the GPS ROOT website) then each day, transfer the route for that day's riding using the Bluetooth connection. Maps for the tour are also manually loaded to the device in advance. And off I go.

There are obvious downsides to this MO the most obvious being the need to stick to your route, but this process works very well for me. This GPS unit has best in class battery life, which is one less thing to worry about and is also far cheaper than some of the more established brands.