They all pretty much do the same thing. I have an iphone and any cheaper phone works just as well. It just matters about reliability and if you think that what you buy is worth it. Look at the reviews and see if that compares with what you want in a phone.
Don't go for canvas series or any phone of MMX. I am also using MMX canvas 2, phone is ok but it and all other Micromax phones are using cheap chipset that is mediatek and it can NOT support higher android version. You can get only till 4.2.2 Jelly Bean version. Beside that it lags as well under simple operations. Also note that some phones like Xperia C also uses mediatek, my advice is to avoid it cause you will never get 4.3 or kitkat.
Between Moto G and Xperia M I will suggest you Moto G as it as better large display with HD resoultion. Quad core 1.2 Ghz processor whereas Xperia M only 1 Ghz Dual core. Better secondary camera, 1MP more.