Which iphone is better from T-Mobile? 4s or 5?

[Alex]

this is going to be my first actually smartphone i have this crappy phone from metro pcs that i had for like almost 4 years. i am planning to go to T- mobile since it has the cheapest plan for the iphones i have a couple of questions,

1) Which phone should i get?

2) Which gb should i get 16 or 32? Im mostly going to use it for music,taking pictures, apps (apps like games and netflix), Internet, and maybe a couple of videos.

3) when i reach to like 2 gb does it slow down the iphone down if i chose the 2 gb data plan? What actually does it do when i reach to that point?

4) Lastly, which color looks best? white or black? and what case may look good on the phone?

Thanks in advance

[Fluffy]

5s because its more advanced
32 gb because more space
Black in my opinon and thats on you c: