Is it the one that has improved the suggestion, or the original creator of the suggestion?
When a suggested edit is improved, it creates two entries in the edit history:
- one for the suggested edit
- one for the improved edit
This makes it clear to see which editor did what.
Here's an example:
As you can see above, both edits have the same time stamp - "14 secs ago", which tells you that they were submitted at the same time.
Additionally, you can see that the edit was "approved" in edit #3, so the person who submitted it still gets credit for it.
If, on the other hand, the edit is rejected and edited, only one edit would appear, that of the reviewer.