I do my Sub bass with NI Massive, but if you want add some modulation, the better way it's to put an LFO on the volume. If you try with the LP it's sound so bad.
There is also a plugin on Windows. I think it's just Sub but it's not really good.
Very Happy with Spectrasonics - Trilian or Rob Papen - Sub Boom Bass. Also your DAW should have a great Bass Synth included. Just spend a bit of time playing with what you have got.
Native Instruments - Massive if you like Dub Step sounds.