Personally, I’m a little biased towards “word count” as opposed to “character/line/page count” as we use in Germany. Still, it would be nice to also have a “character count”.
Reason: The variance of word lengths in English is small, a typical “word” being about 5 characters on average, as far as I remember. In German, we have very small words like “er”, “ich”, etc. and very long words like “Kraftfahrzeug-Haftpflichtversicherung”, “Aufmerksamkeitsdefizitshyperaktivitätsstörung” and so forth, so a pure word count would be misleading.
This is why Germans typically use a character or (manuscript) page count instead of the word count. A manuscript page would be 30 lines of 60 characters each, making for 1800 characters/page, which are typically counted as 1500 characters (i.e. by “VG Wort”) because not every line is full length.
So a character (and maybe even page) count would be extremely helpful for German writers. 
A German writer would probably have something like “I’ll write 5 pages” as a daily goal, as opposed to “I’ll write 1500 words each day” (both being roughly the same amount).