the micromoog is the cheapest, and its bass definatley cannot be argued with. Suprisingly, I have gotten some marriage destroying bass out of the old Yamaha TX81Z, and those are double digit cheap.

If you are using resonance on your bass patches, its a little harder. Without rez, almost any analogish synth can be quite thunderous. But adding resonance is the true test of how well the device can hang on to its bass.

This has to do with the construction of the filter. Filters are either comprised of diodes or transistors. The transistors are famous for maintaining the most bass no matter what, where diode filters tend to get a bit of a whistle or crunch.

Roland chip filters and later devices with CEM filters in them are of the diode type and I seldom use such devices if I want the bass to have that classic moog chirp.

Korg on the other hand designed their AD2069 filters on the moog way and thus the outcome is a smoother, more pleasant more "bottomy" bass. The DW-8000 and even the tiny Poly-800 have this power.

Another thing to look for is the brick wall.
That is anything in the output or mixing stage of a synthesizer that limits bass frequencies for god knows what stupid purpose. If the synth in question has a high pass filter that cannot be literally taken out of the circuit, it will limit bass frequencies.

Suprisingly enough, the micromoog and multimoog suffer this problem, but its easy to get around the bass limiting circuitry inside them. Various websites support.

Roland, on the other hand did some absolutley rediculous things to the audio paths of their gear, like adding chorus circuits and highpass filters, and hundreds of capacitors that muddy up the sound, even when these devices were turned off. Fortunatley, these issues can also be dealt with as the components inside are big enough to solder to and change about.

Older Yamaha CS series subtractive synthesizers all had a slider that let you turn up the sine wave, unaffected by the filter, which resulted in some rediculous bass. The monosynths they made, like the CS-20M are perfect examples of this feature. And they can match the classic moog sound quality, no sweat.