"Up to" is okay, just not very useful. It tells you what you might get, possibly could get, but no indication of how likely you are to get it.
"From" isn't very useful either, because that's going to have to come with a cart load of caveats because sometimes things do just go slower and it's not always the fault of the ISP.
Some sort of average seems better but still isn't a guarantee of anything, nor an indication of what others may get.
The problem isn't so much what claims say but what they mean.