Try   www.PartSim.com  ,  good schematic editor and good ngSpice

and good plots.

I have done several hundred different designs there over the last five years.

http://www.geocities.ws/glene77is/

http://www.partsim.com/

you can use LTSpice it is open source

I personally like the xcircuit, that outputs high quality eps files with nice schematics. http://opencircuitdesign.com/xcircuit/

It is from the same developer of the open-source layout tool, Magic VLSI. 

Check DIA open source

DesignSpark from RS Components.

It is free but you need to register to get a free licence.

http://opencircuitdesign.com/xcircuit/

There is a lot of software - freeware as well as open source - available. Depending on your goals, the schematic entry of circuit simulators like LTSpice might do: see

https://en.wikipedia.org/wiki/List_of_free_electronics_circuit_simulators

For complexer circuits you may consider some schematic entry software: see

https://en.wikipedia.org/wiki/Schematic_editor   or

https://en.wikipedia.org/wiki/Comparison_of_EDA_software