Nem ismerem egyiket sem, de:
GNU Circuit Analysis package
GNUCAP is a general purpose circuit simulator.  It performs nonlinear
dc and transient analyses, Fourier analysis, and ac analysis
linearized at an operating point.  It is fully interactive and
command driven.  It can also be run in batch mode or as a server.
The output is produced as it simulates.  Spice compatible models
for the MOSFET (level 1,2,3) and diode are included in this
release.

Quite Universal Circuit Simulator
Qucs is an integrated circuit simulator which means you are able
to setup a circuit with a graphical user interface (GUI) and simulate
the large-signal, small-signal and noise behaviour of the circuit.
After that simulation has finished you can view the simulation
results on a presentation page or window.

qucs van az uhu.linux.hu-n; eleg hasznalhato cucc. Esetleg a ktechlab-ot is megnezhetned, hatha megtetszik.