Under/Over

Continuing my LotFP tinkerfest:
My biggest bugbear with the current setup is that some rolls are roll-over, others are roll-under. This bothers me, as players get confused as to which way the rolls should go.

As it stands, attack rolls and saves are roll-over. Ability rolls and skills are roll-under. I'd like to align them all in the same direction:

Option A: Roll Over

Move everything to a roll-over system. Attack rolls can stay the same (d20+AB vs AC). Saves would be the same (equal to or greater than your save number).

Ability Score would have to be roll 1d20+Ability. 21+ is success.
Skills would have to be 1d6+skill. 7 is success.

Benefits:

• Rolling high is by virtue of language and conditioning intuitively good. "Natural 20" automatically triggers something in most gamers.
• Ability Scores can be directly opposed, with each side rolling d20+Ability to determine the winner.

Drawbacks:

• Double digit+double digit math is something that will produce an "uhhhh" every time it is rolled.
• Defeats the point of recording skills in pips, as part of the charm was the visual representation on the sheet actually looking like the d6, and needing that or under.
• 21 and 7 sound arbitrary (even if they aren't), and begin to stray into TN/DC territory, which I'm not a fan of for this kind of game. The simplicity of roll-under is that what you see is what you need.
• Save numbers go down to improve instead of going up, which is slightly counter-intuitive. 

Option B: Roll Under

Attribute and Skill rolls remain as they are now. Saves are easily converted to roll-under: you just take what they are now and subtract them from 20. A sheet could have the updated saves and no one would notice the difference.

Attack Bonus would need renamed (it's no longer a bonus), but is functionally the same. If you had +2 before, it would now just be a roll-under of 2. AC would go back to TSR era "lower is better."

Your attack roll would then be a d20  with the goal of rolling under your Attack Score+EnemyAC. 

Bonuses can universally be assumed to apply to the score itself, rather than the roll, so a +1 bonus is still good.

Benefits:

• No math required anywhere except the attack roll, but that always needs math unless you want to make a chart (Note to self: consider chart). What you see is what you need.
• Pips on dice retain their charm.
• All Stats go up to improve - except for AC? Hrm.
• AC listed in other retroclones/TSR material can be used more or less as-is. 

Drawbacks:

• "Roll low to succeed" is inherently less intuitive. "Natural 1" doesn't hit the brain the same way as "Natural 20."
• Enemy AC now modifies your roll, instead of being the target you need to meet. Not sure if this is less intuitive. Could be fixed through a THAC0 style table, but that goes back into "is this more or less intuitive than the alternative? If you did go that route though, AC could be positive as well.

At present, I'm liking B more than anything, but debating whether a return to a THAC0 style chart is better or worse than weird AC mechanics.