I started improvising a nocturne in B major that I think I will write for a piano sextet(string quintet + Piano). But, there is one thing I feel that I need to ask first before I get 25% of the way into the nocturne. And that is, is B major harder or easier on strings than Ab major? I know that the 2 keys are equally easy on piano.
I know there are 2 things that factor in to how easy a key is on strings. Those are positions and the number of accidentals. The natural positions on bowed string instruments tend towards sharp keys being easier. But with the 2 potential keys of B major and Ab major, they seem to contradict on both accounts. Ab major has fewer accidentals than B major. On the other hand, the positioning is more complicated.
B major seems to have a more natural positioning, being a fifth away from E major, one of the easier keys for strings. But there are more accidentals. More accidentals often means a harder key to play in(which is why for chamber works that aren't piano duets, I stay within the confines of 5 sharps to 5 flats on the Circle of Fifths).
The minor key section that is going to appear in the middle of the nocturne to add contrast is related to both Ab major and B major. For B major, it is the relative minor and for Ab major, it is the parallel minor. This really doesn't help when it comes to choosing one of 2 major keys to use. And the 2 keys have similar characters too, often evoking dreamy, nocturnal feelings, especially when slow, as in my nocturne.
So, which key would be easier for the strings? B major, the key I improvised this nocturne in and which gives a very nice plagal relationship to E major(which I will use in my nocturne)? Or Ab major, despite all the flats and less natural positioning?