I second what manus31 said above.
I also haven't got any problem with the moto G coming from a Lumia 730.
Also the battery life is top notch (6+ hours easily of screen on time, with medium to heavy use)
Front firing speaker and some useful gestures with the moto assist:
For example, you can double chop from screen off for activating and deactivating the flashlight (which by the way has really bright dual flashes),
double twist for camera (2-3 seconds without having to interact with the phone at all) and lastly when it is moved/ taken out of the pocket, the screen shows the time and notifications, again, without having to press anything rendering the need of double tap to wake useless (it doesn't have this function).
I first thought that this actions are gimmicky and won't work consistent, but I was completely wrong, they work like a Swiss clock and proven very useful in this week of owning the device. ESPECIALLY the flashlight and the shown time while taking it out the pocket. Motorola has really thought of them!
Also stock android has come a long way and it is a very pleasant experience to use but only if you don't fill it up with all the cr*pware there is out there in the wild such as task killers, ram managers, memory cleaners, antiviruses, etc. In other words, just install apps in logical reasons and don't fill it up with stuff that are promising huge battery or memory increases, they are usually harming your device.
And also the stock android is pretty eye catching in my opinion in contrast to pretty much every 3rd party skin on-top of android mimicking iOS!
(Because no one in his right mind wants a discounted iPhone)
I can say, with the amount of things done using it every day, that it absolutely worth the price-tag.
Again, I agree with manus31 on his Microsoft services,reasoning.
I have installed onenote, onedrive, word, excel and they all work flawlessly and sync without any problem with the PC and tablet, so you won't miss any of the services you already use.
FOR ME, if I had not purchased those phones and somehow had this knowledge and wanted a sub 160 euros smartphone for doing serious stuff RIGHT NOW, I would go for the motoG3. (Given in context that I live in a Country that Cortana is not available, if this helps)
Anyways the choice is yours, I can speak only through my experience with both OSs (as a motoG3 and a lumia 730 owner which is pretty close to the 640)