I would go microKorg Bam. The Monologue is more "synth-y," in that you can do some real hands-on tweaking of parameters, but it is also monophonic (so more of a lead or effect instrument). The microKorg has a number of decent presets for starting points, you can still do some tweaking, but it is more "keyboard-y," if that makes any sense. Plug and play, polyphonic; you could do organ or electric piano type sounds if you wanted to, but also see how you like working with a real (hardware, not virtual) synth and then make subsequent decisions from there. It also has the vocoder and some other goodies. But-- if price is a consideration, it's at least $100 more than the Mono, unless you go used (and there are some out there, but of course, buyer beware)...