Mode (most common element) of a list

max(d,key=d.count)

Since your python answer doesn't seem to print, I expect this is what you want.

Add 6 bytes for print normally.

Matlab/Octave, 7 5 bytes

Unsurprisingly there's a built-in function for finding modes. As an anonymous function:

@mode

This returns the most commonly occuring element in the input vector with ties going to the smaller value.

Saved 2 bytes thanks to Dennis!

eo/QNQ

Try it online.

Expects input on stdin like [4,3,1,0,6,1,6,4,4,0,3,1,7,7,3,4,1,1,2,8]. Ties are resolved by last occurrence because Python performs stable sorts.

Sorts the list by count the value in the list, then prints the last number of the list.

Q could be replaced with d if you initialized d to contain the value before e.g. =d[4 3 1 0 6 4 4 0 1 7 7 3 4 1 1 2 8)

Python-esque pseudo-code:

Q=eval(input());print(sorted(Q,key=Q.count)[-1])

Full Explanation:

            : Q=eval(input()) (implicit)
e           : ... [-1]
 o   Q      : orderby(lambda N: ...,Q)
  /QN       : count(Q,N)

Pyth's orderby runs exactly like Python's sorted with orderby's first argument being the key argument.