You will have everything you need to use the phone just not all the Samsung stuff, like the gestures, and their apps. For every stock Samsung phone app there is a Google alternative such as the Calculator, Calendar and email. The Google phones don't include the battery percentage that you can enable in the normal settings. You have to enable it in developer options and it's still not the same ( I actually like the Samsung implementation better.)
In stock Android you had to download an app to have a different lockscreen wallpaper, but with 7.0 it's built in like Touchwiz. In the email app on Samsung phones, the lowest you can set the interval to check email is 15 minutes, on stock Android it's 5 minutes. Whenever I've had a stock Android phone and a Samsung phone, my emails always came faster on the stock phone. The Samsung camera app has much more options.
I think it just depends on what you liked to use on the Samsung phones. I like the theme store that Samsung had, but it was only because I could choose a marshmallow, stock looking theme. Those are some of the things I remember, other than what's already been posted about. I'm a stock Android guy, but there are still some features on Samsung phones I like better.