When you install watchOS 5, you have the option of starting over fresh with a clean install or you can install the software while maintaining all of the apps and settings you're used to working with. It all depends on your preferences and usage habits as to which option is best for you.
Why a clean install of watchOS 5 is a good idea
A clean install is tabula rasa — you get to start over anew, making an older Apple Watch feel like a brand new Apple Watch and helping to keep your new Apple Watch feel as squeaky clean as the day you bought it.
This also gives you a chance to ditch all the data that may be stored on your Apple Watch that you don't need. You can then purge that data from your iPhone while you're at it. Think of it like cleaning out the garage before winter comes so that you can start parking your car in there.
Since most of the data on your Apple Watch is already communicated to your iPhone, it's not like you'll be missing anything you delete and/or reset, and you can always re-sync your Apple Watch with your iPhone to get some things back.
Just remember that if you perform a clean install, you'll probably have to spend some time setting up your Apple Watch again. You may need to re-enter passwords or update certain apps on your iPhone in order to get everything up and running again.
Why a standard installation of watchOS 5 is a good idea
Plain and simple, you can take it all with you, so to speak. You get to keep all your apps on there, including all the saved data and whatnot, and you don't have to spend a ton of time setting up your Apple Watch over again, which can be a HUGE pain in the ass if it happens to freeze or simply decides to take its sweet time (not that that's ever happened to me before, of course). Instead, you can just update and get going again.
Which one is better?
It really depends on your personal preference for this one. It's not like a ton of data is stored on your Apple Watch. Most of it is on your iPhone, so it's not like you'll lose absolutely everything if you decide to go the clean route. And since it's much harder to get into the inner workings and settings of an Apple Watch than an iPhone, it's probably a little better to go with a clean install anyway.
How do you do the dew?
Do you prefer a clean watchOS install or do you like to carry everything over? Let us know in the comments below.