Source is official Frieren twitter. I have transcribed and translated the top 20 below. I am not great at Japanese, so can’t claim to translate the whole list, but I also included a couple other notable characters in a table further down.

Rank Character
1 Himmel
2 Frieren
3 Mimic
4 Macht
5 Fern
6 Stark
7 Denken
8 Hero of the South
9 Sein
10 Aura
11 Heiter
12 Land
13 Übel
14 Solitär
15 Serie
16 Flamme
17 Eisen
18 Methode
19 Wirbel
20 Sense

Other characters I was able to pick out pretty quickly:

Rank Character
34 Linie
41 Kraft
48 Graf Granat
50 Lugner
56 Sein’s Brother
92 Draht