I like Mayfair's DC Heroes RPG's system:

Every die roll you make (combat, skill, etc) involves the following:

There are four numbers that matter. In combat, the first two would be the DEX scores of both combatants (or a skill that replaces DEX or whatever) and the second two would be the STR (or other damage value) of the attacker and the BODY (plus modifiers possibly) of the defender. In skill checks, other numbers are used obviously, but there's always a "see if you hit/succeed" part and a "see how well you succeeded/how much damage you dealt" part.

There are tables for each of these two parts. The first table deals with "see if you hit/succeed". The dice you roll are 2d10 (with "exploding" dice, meaning roll again and add when you get doubles) with a result of 2 being an automatic failure. Against an equal opponent, you need to roll an average roll of 11 to hit/succeed. For lesser opponents, you need a smaller number; for more difficult opponents, you need a larger number. (These are all on the table.)

If you roll more than an 11 and also succeed, you may get "column shifts". This indicates that you have hit better than normal or you have succeeded better than normal. The higher you rolled, the more column shifts you get. These will "shift" your results on the second table to be more beneficial.

On the second table, you compare your STR (or whatever) to your opponent's BODY (or whatever). There will be a number on the table that represents how much damage you deal (or how well you succeeded), but then the column shifts will move your result to a column with bigger numbers.

And the best part is that, for tasks with unclear difficulty numbers, there is a table that lists appropriate numbers depending on how difficult the GM thinks the task should be, ranging from "easy" to "Herculean".

Climbing a wall with handholds? Easy. Climbing a wall without handholds? Difficult. Climbing a sheer glass wall covered in slippery oil? Herculean.