they're all pretty worthless. the closer it is, the faster its gonna be. find a FAST ftp server somewhere. try a bunch of different ones. eventually you will find one that hits your cap, whatever it may be, and assuming you're not on a T3. then try these "bandwidth testing" sites. they will all be different.
for example, before my cable got capped, my fastest speed was about 6Mbit. that was to a fast ftp server somewhere (dont remember where) in the US, and random other places i'd download from. so that was my TRUE bandwidth. yet dslreports told me i was about 1800kbps. either way, its a mixed bag. it depends on where you're down/uploading from/to, and it depends on basic internet weather conditions. even if you can hit 5mbit, many or most of the sites you visit will not transfer at that speed.
SO. stop wasting your time on theses sites. find a fast site and figure it out for yourself. 8 bits equal a byte.