The less software (beyond stock Android) that a phone has, the better off it is IMHO. My last Moto phone (a G4) was almost entirely stock and that made me more inclined to buy the new version. Unfortunately the new phone had a bunch of bloaty apps but I managed to remove or disable almost all of them. Many of them were from Google if that matters. There is an app called Universal Android Debloater (UAD) that does this automatically but I didn't find out about it til afterwards.

I'm not noticing any ads from the software on my phone. I am still working on replacing the Google stuff though, since it is presumably spying even if it isn't spewing ads.

On a recent iphone setup I didn't notice ads per se, but instead there were constant pitches to buy subscriptions to Apple services. I found that just as bad as ads.

The Moto G's currently come with 3 years of security updates and 1 Android major version update. That is probably good enough. More than 3 years out, the phone hardware probably can't keep up with the increased levels of software bloat. My old phone had 2GB of ram which was fine when I got it, but near crippled now.