AT is by far the most common as a simple preposition. AT is also used in adverbial phrases which we have listed in order of most frequent according to iWeb corpus and then given examples of their usage in sentences:
1 AT ALL 1232801
Maybe they weren’t thinking about anything at all.
2 AT FIRST 403759
I thought they worked for the government.
3 AT ONCE 222526
Don’t everybody thank me at once.
I assure you I did.
Obey me at once.
4 AT BEST 111972
and your family will be broken.
5 AT PRESENT 83432
I wouldn’t like to be in that boy‘s shoes.
6 AT LAST 77484
7 AT MOST 61078
8 AT LARGE 57046
9 AT RANDOM 36452
10 AT LENGTH 32751
Well, I can talk at length about that.
ALL AT ONCE 54444
I think Sarah threw a little too much information at David all at once.
AT LONG LAST 7739
Because I see, at long last, what‘s wrong with the world.