Still the combinators/circuits...

[Factoruser]

The decider combinator should serve "IF ... THEN ... ELSE" blocks. One line is e.g.
"IF item1>value THEN item2=1 ELSE item3=1", "ELSE" of course optionally.

The current system is rather useless, because you can only send one signal for several conditions and not even an alternate signal. This leads to very complicated and error-prone wire salad for very simple tasks like "IF iron-plate<200 THEN iron-ore=1", "IF copper-plate<200 THEN copper-ore=1" and so on in separate decider combinators each.

To get a logical AND, you might have the result option <signal> AND 1. => Condition #1 "THEN item2=1", condition #2 "THEN item2 AND 1", i.e. the AND operation is performed on the previous output signal. This "trick" has to be documented in the Wiki/factoriopedia of course.