Those all look valid and within a reasonable range.
I have found the most reliable to be http://mcslhr.visualware.com/myspeed/myspeed_line_ca...
is also quite good, and thinkbroadband used to be (but seems unalble to handle FTTC well). But remember that any speedtester is just a diagnostic tool, and that results will vary from day to day, with changing traffic on the internet and on the speedtest site.
There are sometimes very odd cases where they are completely invalid. A few years ago an oddity of the way Kaspersky handled traffic meant that many speedtests would report speeds 10 times faster than the maximum the line could possible manage. I find for me (on FTTC) that the BT tests tend to give around 1/2 the proper value for upload. What really matters is the real speeds you get to real sites.
Moved (with trepidation) to BT Infinity 2 for upload speed. Happy BE user for several years.