Which sentences are grammatically correct and which one sounds the most natural to you?
- Speaking English is not as tough as it used to be.
- Speaking English is not tougher than it used to be.
- Speaking English is not tough as before.
The first implies that speaking English is easier than before, whereas the second indicates that there has been no change in the difficulty.
Sentence 3 is ungrammatical, though adding as before tough would fix this and the meaning would be nearly identical to the first.