Which command among all commands in autocad you like the most and why?

Ctrl Y, Ctrl Z, Ctrl C, Ctrl X, Ctrl V etc

 The Trim  is use to Cut the extra line

The most powerful yet simple command which we use often in the major industries (Both Civil and Mechanical) are "XREF" and "BLOCK (B)".
For the beginners the block creation, block editor, Dynamic blocks and attributes seems a bit confusing and complicated but they are the best when you get use to it.

HATCH (H) ...
Simple and easy and makes your CAD drawing colorful and presentable.

l=line, o= (offset), tr, m(Move), la=layer, Ch=chamber, fi, ma= match property.

mirror & copy & move making your job faster

 (1) HATCH (H).

Simple and easy and makes your CAD drawing colorful and presentable.

 

(2) BLOCK (B).For the beginners the block creation, block editor, Dynamic blocks and attributes seems a bit confusing and complicated but they are the best when you get use to it.

Copy, of course!!! Because you can take autocad entities from other drawing/same drawing and can be used multiple times,Were as other common commands like move/mirror you have to create it first then can solve repetition making your job easier..