Screen Size: Screen size plays a big role in which phone people get. Samsung has the Galaxy 3 and 4 which have nice large size screens. The average size screen is about 5 inches. You can get devices that are larger but those tend to get a bit bulky. The Iphones are around 4-5 inches depending on model.
Storage: Iphones come with standard space 16, 32, 64 GB models. Most Androids have the same but with one big difference. Android phones have a micro SD slot built into them so that you can expand the phone. Most phones will except 32 GB cards.
Camera: All of the phones that are on the market today all have cameras with flashes built into them. One of the androids that I looked at had a 12 MP camera which for cameras in phones is pretty good. There are some that are even better then that but anything about 15 MP (Mega Pixels) you really should have an actual camera to take the picture. People for a while now have been asking for the flash to become a flash light. Android was the first to build this into the phone for people to have. Iphone has now come out with this in their newest software update.
Last but not least:
Cost: Depending on where you are with money, your cell contract this could be a big sticking point for you. It might make since to buy a used phone instead of a brand new one. Just remember when buying a used phone make sure to take the phone to the cell phone store to ensure that the phone will work when you buy it and activate it on their network.