Hi Michael,
Welcome to the world of modular synths!
The answer to your question is obviously subjective, but I'll give you my $.02:
The MOTM 440 filter is my favorite, having an incredible sound and optional enhanced bass response. MOTM also offers the 480, 485, and 490, each with its own character. It really depends on what you are looking for in a filter. Each of these is an emulation of a classic analog filter; for example, the 490 emulates the Moog ladder filter.
I have built several Synthacon filters, and I like it very much, mostly in lowpass mode. If you intend to build your own, research the many mods documented on the Web before you begin.
I also have an Encore Frequency Shifter, and I find it most useful in creating subtle animation to liven up drum tracks, for example. One advantage of this module is the availability of the sine and cosine waves, both with attenuators.
Your best bet would be to listen to sound clips and decide which sound would be most useful for your purposes. Once you are bitten, you are sure to acquire all of them over time.
~Terry
--- In motm@yahoogroups.com, "Michael W" <mikewelch7@...> wrote:
>
> Hi,
>
> I'm beginning to build a modular synth in the MOTM format and received my first sets of modules this past week. I had a blast this weekend with the 420 filter and the Oakley Equinox phaser, which sounds incredible!
>
> While I need some basics, such as a rack case, Midi / CV converter, I'm really having fun using my evolving modular as an effects chain for my DSI and Moog synths.
>
> What are everyone's favorite MOTM filter or effect?
>
> Some I'm looking at include the Encore Frequency Shifter, the Synthacon Filter, etc.
>