There are some skills for which it is impossible to accurately determine the relevant factors. To do so would require thousands of hours of gathering sample data in order to establish a statistically significant correlation.

Here are a couple of them and the subtler factors that could logically have an impact (and aren't completely obvious).

Assassinate (from the point of view of the assassin):

Stalk amount (is more ever worse?)
Stalk quality (is stalking within-room better)?
Vuln hitting (is it better?)
Weapon skill (is having higher better?)
Weapon weight (is heaver or lighter better)
Weapon type vs class (Is using a target-unlearnable weapon better?)
Carried weight (is lighter better?)
Wearing glowing (does it hurt?)
Wearing humming (does it hurt?)
Target Position (is sleeping/resting better?)
Time of day (is night better?)
Darkness (are dark rooms better?)
Target Con (is low con better?)
Target Dex (is high dex worse?)
Self Dex (is higher dex better?)
Self Str (is higher str better?)
Self damroll (is higher damroll better?)
Self hitroll (is higher hitroll better?)
Self Food/drink (is full/sated better?)
Target Food/drink (is full/sated better?)
Target health (is lower hp better?)
Self Preps (is haste/quicken better?)
Target preps (is dam redux worse?)
Target preps (is haste/quicken worse?)
Poison Darts (is (sleep || confusion) better?)
Size differential (is target-bigger better?)
Self Morale (is higher better?)
Target Morale (is higher worse?)

Choke (from the point of view of the whip-spec):

Target Entanglement (is entangled better?)
Vuln hitting (is it better?)
Weapon skill (is having higher better?)
Weapon weight (is heaver or lighter better)
Weapon type (Is whip or flail better?)
Target Con (is low con better?)
Target Dex (is low dex better?)
Target Str (is low str better?)
Self Dex (is higher dex better?)
Self Str (is higher str better?)
Self hitroll (is higher hitroll better?)
Target health (is lower hp better?)
Self Preps (is haste/quicken better?)
Target preps (is dam redux worse?)
Target preps (is haste/quicken worse?)
Size differential (is target-smaller better?)
Self Morale (is higher better?)
Target Morale (is higher worse?)
Target saves (is sv paralysis worse?)

And for that matter, what about bash? Everyone always says "it's mostly xyz" and that's fine, but how many small factors are there that you could never, ever figure out? The basic problem I have with this sort of stuff is that it just makes people superstitious. We're all relegated to practicing voodoo because there's no way of knowing what really matters and what doesn't.