Although the Fire 7 is indeed laggy out the gate, the HD 8 and HD 10 aren't. Using the Fire Toolbox to disable the preloaded bloatware allows the HD 8 and HD 10 to be pretty snappy. For quite a while, the HD 10 was my only Android-based tablet and it was quite adequate. I have a few Amazon Fire-related threads here on MR where I document my experiences.Amazon tablets are laggy enough out the gate. I can't imagine how bad it is with the heavy usage of Play Store/Google Play Services added to it. Those two are the first things I disable on any Android device, just after disabling software updates.
You all should look at the level of permissions for just Play Services. It's scary. Disabling it on my Note II nets 2 days total battery life, over what would normally be 8-12 hours standby with it enabled.
Regarding the drag of Google Services on battery life, I think that it highly depends upon the device that it is running on. On my older smartphones, it does indeed seem do a lot of background stuff. On my Tab S6, only minimal drain (I've run tests with it in airplane mode and not and the difference over a 12 hour period is 2% of battery life drain).
On the Fire HD 8 with Google Services installed, the battery percentage drops 1% over a 12 hour period with the tablet in standby. (without Google Services, there is a 0% drain)