Most Accurate Speed Test Site

[#1]

Hi,
What is the most accurate site for checking the speed of my fibre line?
I conducted two test using Broadband Speed Checker and BT Wholesale and got vastly different results as follows:
Broadband Speed Checker
1st test: 24.86 download 48.40 upload (I haven't mixed the download/upload figures up!)
2nd test: 39.54 download 22.91 upload
BT Wholesale
1st Test: 49.10 download 15.53 upload
2nd Test: 48.92 download 14.91 upload
Thanks

[#2]

Probably this one http://www.thinkbroadband.com/speedtest.html?utm_source=mainsite&utm_medium=navigation&utm_campaign=...

[#3]

I agree with OldJim.  Particularly for upload tests where many speed testers give values that are way below good real world values.
broadbandspeedchecker seems particularly unhelpful.
Sometimes AV or firewall code can distort values, and not just by causing slowdown.  Kaspersky was a particular issues a few years ago; the way it buffered things up confused many speedtests.  I got readings of over 100Mbps (on a 20Mbbps connection) and others saw even more extreme silliness.  It wasn't significantly affecting real downloads/uploads, just speed tests.

[#4]

Thank you.
The readings I received were consistent each time I ran the test and similar to those I got from the BTW site.
Thanks.