First, it would be helpful to know your anticipated price point. Secondly, it would be useful if we know how proficient you are with tweaking sounds vs just wishing using presets with minimal tweaking.
Synthmaster, for example, is a huge value for raw bang for the buck. But to take full advantage of a large collection of presets, you would want to purchase quite a few of the expansion packs (and there are some very fine ones available).
Rob Papen Predator 2, on the other hand, costs more than Synthmaster and doesn't have the range of Synthmaster in terms of types of sound production possibilities (no sample playback for example), but it comes with thousands of immediately usable presets (and a good browser for finding types of presets you are interested in). You could easily make an argument that Predator 2 is the better value based on the presets it ships with.