I'm in the same boat. I'm a 6S+ owner and have been tempted by Android for awhile since I'm using Google services.
After a few days, I'm on the fence about Android for a few reasons:
1) iOS/OSX integration is tough to give up. Being able to take calls/answer texts is very nice functionality. I can use Google Voice, but I've found the service to be a little flakey
2) Text selection and copy/paste is smoother on iOS. Being able to highlight a single word has proven to be a mixed bag as far as performance. Obviously, this is a minor issue
3) Tough to make a definitive assessment after a few days, but battery life seems better on the 6S+
4) As mentioned by many others, update speed for Samsung phones is horrible compared to iOS. In addition, I've read accounts where Samsung updates have crippled performance on the S6 so that is a concern.
5) Not a big fan of the multiple app stores. Getting Amazon Video app on my S7 Edge was a hassle (and I'm not sure how I know when the app gets updated since it's not in the Google Play Store)
As far as the S7 Edge, I love the design, screen and camera. Google services are decent on iOS, but fantastic on Android devices. I have not seen much lag on the S7 Edge...only slightly more than the 6S+ so I would not consider that a deal breaker by any means.
Also, I would say that the app quality on Android has improved greatly since the last time I was on an Android device. Perhaps there is a more consistent design language for iOS apps (though there are many apps that are still not updated for the larger screen devices) but I prefer the material design language of Android.
In the end, it's going to be weighing the iOS/OSX integration vs the superior Google services on Android.