Mine last for a long time(1750mAh)... however, the the larger mAh will definitely goes further.It doesn't take a mathematics genius to figure out that the 1750mAh battery doesn't have much more juice than the stock 1500mAh one. After all, it's only 17% more powerful. A 3500mAh one, however, will last much longer because it has 133% more power than the 1500mAh one.
I prefer a more flat shape phone, rather than a bulky looking one.