There are dozens of speed tests available, plenty of free ones. Rather than say X, Y or Z is best, I would recommend using a number of them and making samples one after the other, say three speed tests, then if they match you know, otherwise work out an average if there are not enormous discrepancies but if there are big differences do it again. I have been down as low as 1.31Mb/sec a few weeks ago, when I spoke to Orange they told me that was impossible, so I explained I had made four speed tests, told them which ones and then left it an hour then tried two again. That speed was reasonable. So then the 'technician' said that he had just been looking at the plan of the area and saw that we are on an old copper line. I said that three new phone lines have been added over the last year and a bit with a fourth soon and asked what difference that might make. He did a big 'Ahhhh!' and said that we probably need our line updated. However he saw nothing to indicate it was going to be soon. I told him that the departmental plan of two years ago left our 'corner' of this commune that was low down the list anyway, was outside of the then 12 years projection. His answer was to contact the people responsible in the department rather than Orange.
At present I have around 3Mb/sec on average, some friends who also live in the sticks but happen to be spitting distance from where fibre optic lines were laid for the sakes of several businesses in the area, they were upgraded and have something like 12Mb/sec. We pay the same of course.