Which Speed Tester should I believe?

[#1]

After a mystery router restart this morning, I thought I'd do some speed tests. The results were:
                                        Down /  Up
BT                                    2970  /  368
Think Broadband                3209  /  379
My Broadband Speed        3555  /  384
Which result should I believe? 

[#2]

You can run a number of speed tests over a relatively short time period using the same site and get variations so none are 'guaranteed accurate'.
It would depend on a number of factors at the time of each test.
This is a lovely piece of speed test software http://www.gmwsoftware.co.uk/ showing the variation over time of my connection below.  

[#3]

Strat - I agree about that piece of software - I've been using it for a few days now and it looks very promising  
Mfiles

[#4]

That makes for interesting reading.

[#5]

Lower but more consistent than mine which illustrates a persistent drop in D/L speed at around 8:30 every night

[#6]

It does present things in a way which highlights issues/odd-balls - My Ping stays steady at about 32ms until 5pm and then goes up - This is not a problem for me but as I say, it highlights things without having to go digging for things.
You can leave it running without any intervention....  I'll see if I feel the same in a month's time