If you only have one set of effect plug ins then spundtoys is the way to go. The effect rack can hold multiple devices and you can control them all from one knob. Extremely versatile and going way beyond most with the intuitive tweakability. The Crystallizer and Tremelo  is particularly nice but so are they all really!!
Soundtoys 5 brings together our entire range of audio effects into one powerful collection. Includes all 18 Soundtoys plug-ins. 
Saturate,
 compress and distort with Decapitator, Radiator, and Devil-Loc. Get a 
virtual history of echo and delay hardware with EchoBoy and PrimalTap. 
Transform your vocals with Little AlterBoy. Recreate classic studio 
pitch, chorus and widening effects with Crystallizer and MicroShift. 
Take modulation to new levels with the beat-synced rhythmic effects of 
PanMan, Tremolator, FilterFreak, and PhaseMistress.
All of these 
individual elements are proven, powerful tools, trusted by professional 
mix engineers, musicians and sound designers everywhere. But combined in
 the new Soundtoys Effect Rack, they are indeed the ultimate effects 
collection.
The new Soundtoys Effect Rack is the centerpiece of 
Soundtoys 5. It turns a tried-and-true collection of powerful individual
 plug-ins into a virtually unlimited creative multi-effects system.
The
 Effect Rack makes it simple to build your own custom effect chains and 
define your signature sound. And when you’ve created the perfect 
combination of effects, the Rack’s global controls let you treat the 
whole rack as a single plug-in.
Lock rhythmic effects to a single
 tempo, or let them run free. Fine tune the input and output levels, and
 use the global mix control to blend your effect in with the dry signal.
 Then experiment with the powerful new global Recycle control. By mixing
 the output of the rack back into the input, you can build your own 
modulated reverbs, over-the-top delays and other unique ambience effects
 that would require complicated routing to accomplish in most DAWs.
Work Smarter
The
 Effect Rack integrates all of the individual Soundtoys effects into a 
single plug-in, which improves workflow by displaying an entire custom 
effect processing chain at once. You won’t need to juggle multiple 
plug-in windows to adjust parameters, add new effects, or change their 
routing. The Effect Rack keeps everything right at your fingertips.
Choose
 from our range of carefully-crafted presets to find the perfect 
jumping-off point. Or quickly design, save and recall combinations of 
your favorite Soundtoys effects—all in one self-contained plug-in.
Effects that move to your rhythm. With any shape you can imagine.
An
 LFO (Low Frequency Oscillator) is at the heart of every modulation 
effect — it’s what gives tremolos, phasers, panners and sweeping filters
 their characteristic motion.
Our included library of LFO shapes 
goes far beyond standard modulation effects, giving you curves based on 
vintage modulation effects, amps and instruments as well as more 
abstract shapes. You can also draw and sculpt your own totally 
customized shapes using our Shape Editor. Use it to dream up new LFO 
shapes, from knife-edged waves to gently ebbing curves.
Our 
Rhythm Editor is like a rhythmic modulation sequencer. Choose a length 
(in bars) and the size of the steps you want to edit (sixteenth notes, 
eighth notes, quarter notes, etc), then start clicking to make a new 
pattern. You can turn individual steps on and off to create pauses or 
rests, and adjust the level and length of each step to humanize your 
pattern and give it some musical variation. You can even choose the 
number of beats per bar to create some funky syncopation or 
odd-time-signature grooves. Like our custom shapes, custom patterns are 
even swappable between plug-ins. And, of course, you can lock everything
 to the master tempo of the Soundtoys Effect Rack or your favorite DAW 
for solid, dead-simple synchronization.