Practical English Usage
Michael Swan
Third Edition
pg 111
pronouns after as
In an informal style we can use object pronouns (me, him etc) after as.
• She doesn't sing as well as me.
In a formal style, we prefer subject + verb after as.
• She doesn't sing as well as I do.
A subject form without a verb (e.g. as well as he) is unusual in this structure in modern English.
@Felix_Wan