I will eventually need to upgrade my old Samsung Galaxy S3. (No laughing, please!) I use my smartphone though out the day for google inquires, text, instagram, email, and occasionally take a photo. I carry my camera almost everywhere I go and it has wifi capability. The only game I play is Solitaire. I would prefer that my new phone have a removable battery and 4g memory. Please advise, based on my phone needs what type of phone I should purchase. I prefer Samsung, and not some type of Windows phone. Unlocked? Just not sure. Thanks