I was leaning to EZ-4 but thought of looking around a ltile more and so i'm asking fo your opinions

sionce i have never had any sort of gba flash cart I don't know much about them
I own a normal ds so all the ds lite only carts don't go

I have R4 (duh r4 section) the extra ram would be nice I also will play gba games on it and rumble is a nice extra thing but not neccesary
so what's the biggest difference between them?
and wich one is the best?

 

I have R4 and the 3 in 1 Expansion Pack for EZ-Flash V and never had any trouble using them together. I really don't know the differences between EZ4 and my version, but I recommend you the one I'm using for several reasons:

-GBA Compatibility/Rumble Pack/RAM Expansion
-Low cost
-Good build quality and colors available (bleh)

Both CycloDS and EZFlash SLOT-1 carts offer native support for this SLOT-2 cart. The other cards will require a homebrew app (GBAExploader) in order to make the cart features work.