Personal Input: Smart Phones

Hey there guys.

Lets talk about smart phones.
When you get phones like the android or iphones or whatever, do you get it right off the bat?
I have smart phone from t-mobile and it sucks ass.

When I first got it, it was running smoothly and fast.
As soon as I got one or two apps on it it starts to slow down like hell.

I had this problem with the iphones as well.
Download a few apps and it slows down and uninstall still slow as crap.

I need a new phone and I need to know whats good.
In your opinion, should I get a new android phone or another iphone?

Tell me what you think.