I don't mod at all, I've got a Nexus 6p and am confident it is the perfect phone right now.
One flaw: tough to repair (2/10 on ifixit [0]) which will be fun when the battery starts to go.
Another issue: Android Marshmallow (admittedly not Nexus-specific) doesn't play well with AdBlockPlus, and if you want AdAway or another hosts mod, you still need root. Rooting will allegedly break Android Pay, too.
You may also install the Firefox android app then add the Adblock extension
Also there are lots of other android Chromium browser apps in the playstore and many with ad blocking built in
My experience "hacking" my Nexus 5 to enable WiFi hotspots, without paying sprint for the service, required root, and the process took maybe five minutes.