Iphone 5 umberable Wi-Fi and lte speeds?

I have literally probably tried everything from changing the dns using name bench to proxy, i have updated everything turned off services but still the Wi-Fi on my iphone 5 is so slow! Slower than my ipod touch 2g i even went to verizon to show so they changed my s and it didn't change anything! What should i do help me!

Added (1). I have tried reseting btw and hard reset but not restore

What is a good phone, iPhone 5, Samsung Galaxy S2, or Samsung Galaxy S3?

I need a new phone and I'm wondering which I should get. My friend is selling his GS2 for around 50 Bucks and I could possibly get an iPhone 5 or Galaxy S3. Can you tell me the prices with and without the plan. And for people that have these phones could you tell me how good it is and which carrier(Sprint, Verizon, At&T)?

Can i use a iphone without a data plan?

I'm planning to buy someone's iphone and i'm wondering if i need to use a data plan on it? My friend and my cousin both bought it from someone and they both don't have data plans. How is this possible? They said to turn off data in the settings, but does it really work or not?