I have the 1.15 and the 1.05. I wouldn't go below the 1.05 as it may be too mild. I think I prefer the 1.05. Have the WHR1 & WHR2 handles - both are great.
I'm used to pretty mild, but also appreciate that gentle, but efficient is often better for sensitive skin in terms of less passes, buffing etc. My preferences are Fatboy on 4 or 5, 6S on 4 (can go to 3 with a Nacet), various Techs. OTOH, a Feather Popular and a 40's style SuperSpeed are too mild and I get irritation from too many passes.