aperi, my firm belief is that players are considered by abilities, not attributes. meaning, a good defense player is a good defensive player is a good defensive player. i think its true high ath guys tend to draw fouls on low ath guys - but i think that is simply because high ath guys tend to draw a lot of fouls, and low ath guys tend to be bad players, giving up lots of fouls.
now, dont get me wrong - players of equal defensive skill are not all created equally. one with better def will hold opponents to lower fg%, one with better spd will get more steals (avoiding the fga altogether), etc... but i do NOT think the game is comparing the off player's ath or spd or any single attribute, to that of the def player. i think it looks at overall abilities.
ath/spd are both significant in getting to the line, especially ath. bh is important for interior scoring but im not sure how much impact it has on getting to the line - its probably decently important. im just starting, now, after all these years - to really use interior scoring. i was a 3pta shop with literally every single good team in my life, up to now - i have the first and only good team of my career, that is not 3pta driven, in d2 tark right now (by good, i mean by a safe margin, #1 in the country). one of the major points i have to investigate still, is the impact of bh on interior scoring.
anyway, when you ask about what is more important in interior scoring, thats not a simple answer. any simple answer is largely misleading. id go with LP if i had to pick just one - but 50/50 vs 20/80? damn, i mean, those are both awful. id take a 99 ath 1 lp scorer over 1 ath 99 lp, by a **** ton (just on offense). you can be effective with a lot of ath, without much lp - but not the reverse. however, for a highly effective scorer - say in d2, 80 ath/90 lp - 1 point of lp is going to be more valuable (just on offense). assuming a big type player... for guards, its probably ath. its really not a simple question/answer.