My first sensei used L kamae with a straight front foot.
My next sensei used L kamae with a slightly out turned front foot.
My current sensei uses straight kamae. He has an extensive iaido background.
All 3 of them have good reasons for the way they stand.
I had knee problems when I trained with my second sensei.
I prefer no 2.However it takes a bit of time and effort to get used to it.No 2 opens up the hip joint.
No 3 I assume is a bit Iaido related, this is understandable.Nevertheless Iaido is not in terms of posture the same as the stance in Aikido body art or Aikiken/jo.These function on hamni.
No 1:Comfortable stance , ok as long as knee/s are relaxed and the toe /foot does not turn inward.