Electronic – Switching 12V with an active low 5V signal

If you wish to avoid holy wars you'll need to avoid making simplistic and incomplete statements :-).

Bipolar transistors are current driven.

MOSFETs are voltage driven.

In both cases the spread of parameters during manufacturing is such that a circuit will almost always rely on feedback to produce a given voltage or current gain.

MOSFETs tend to be slightly more costly at the very bottom end for "jelly bean" applications. But, for switching more than a few ~100mA, MOSFETs are usually as cheap or cheaper than functionally equivalent transistors, are easier to drive from a uC (microcontroller) as a digital switch than bipolar transistors and tend to have very significantly superior on characteristics.

An "on" bipolar transistor exhibits a saturation voltage. This can be several tenths of a volt and to get it much under 0.1V usually requires a high base to collector current ratio that is undesirably high. At 1 A a 0.1 \$V_{sat}\$ (saturation voltage) dissipates 0.1 W and is the equivalent of a R = V/I = 0.1/1 = 100 \$m\Omega\$ transistor. But at 10A the figures are 1 Watt dissipation and 10 \$m\Omega\$. The 0.1V is very difficult to achieve at higher current levels.

The \$R_{DSon}\$ (Drain-Source on resistance) of MOSFETs is typically under 0.1 \$\Omega\$ and you can get devices with 10 \$m\Omega\$ or even sub 1 \$m\Omega\$.

As switching speeds rise MOSFETs need a gate driver to charge and discharge the gate capacitance. These can be relatively cheap.

More soon ....

What @IgnacioVacquez-Abrams is talking about in his comment is creating a Push-Pull output. This is basically what is in the output stage of your Microcontroller.

^{simulate this circuit – Schematic created using CircuitLab}

When the PWM is HIGH Q1 conducts. The gates of M1 and M2 are then both LOW, so M1 is on and M2 is off. RL and CL are effectively connected to +12V. When the PWM goes low Q1 stops conducting, the gates of M1 and M2 are pulled up to +12V by R1. M1 turns off, M2 turns on. RL and CL are then effectively connected to ground.

It is important to select MOSFETs M1 & M2 with gate threshold voltages sufficiently high so that both FETs are not ON when the gate voltage is in-between 12V & 0V. This is one place where you do NOT want to use logic-level MOSFETs.