Getting back to size being a trigger...
My initial bi curiosity was driven by my interest and desire to see, feel, and experience a big cock.
No that I have been bi for a couple decades big dicks still are a trigger to engage with a guy. Just seeing pictures of big cocks causes an inner ache to be penetrated and have my prostate stimulated in a way only size can!
However, my desire and acquired taste for cum that's grown over the years has me craving any size cock to orally pleasure for the reward of fresh semen to feast on. I just prefer it well groomed, clean, and attractive. Feeling a cock grow hard in my mouth, throb and pulse as it ejaculates its load, is so pleasing for me!