@trmentry - Great question. This is something I've given thought to, personally - with my own plans to sell my home in the near(ish) future.
Regarding a Factory Reset, I do agree with the opinion below...
In addition to the above rationale, Factory Resets performed while the controller is still on an account have been known to put the controller in a rare state of "limbo" - still registered with the Rachio cloud, but devoid of local settings. So... don't do that.
The simplest solution involves deleting the controller from your account, so they can take it over later. see: How do I delete a controller from my Rachio account?
Beyond that... he short answer to your question is, well... it depends!
Q: How "hands on" do you want to be with the new home owner?
A1: VERY HANDS-ON. I love my yard, and want to make sure it's not neglected!
If you'd like to guide them, personally, through all the settings and schedules you've perfected, you can simply Share Access of your Controller until they're ready to take it over. Delete the controller further down the line, but let them know they'll have to re-input the settings at that point.
Unless you're running Fixed / Flex Monthly schedules, however, this may not be optimal. A consistent WiFi signal is preferred for Flex Daily schedules, in particular. (to avoid a "grey-area" default) Fixed & Flex Monthly will continue to water, but will obviously be less "full featured" without the internet.
A2 SOMEWHAT HANDS-ON. I'll leave it to them, but provide them with tips.
Go ahead and delete your controller, as mentioned up top, but be sure to take note of all your settings first.
I may take this route, myself, through a combination of screenshots (web app) and old-fashioned paper&pencil type notes. Your preference, of course, but it may be good to leave the orignal documentation with them as well. (i.e. Quick Start guide & Limited Schedule booklet)
For the landscape to continue getting water without being connected, the Gen2 has Limited Schedule capability. Instructions on how to set that up should have come with your device, but are also available in this support article.
A3: HANDS-OFF AS POSSIBLE!
Simply Delete the controller from your account, as above.
**If you're in wintery climes, like here in Denver... you might want to winterize your irrigation system to prevent possible damage.
Hope that helps! (for OP or anyone else facing this dillemma)