Electro Harmonix Synth9 Synthesizer Machine

This pedal is great fun and offers a lot for the money. The 2 control knobs allow for a far greater range of sounds than the "9" implies. Tracking on guitar is excellent in standard tuning and drop D, but certain sounds might be more sensitive than others to how you play. You do need to adjust your playing style sometimes to get the best sounds out of this pedal. Overall though, you get a great range of usable sounds with no noticeable latency.

The negatives - there's no way of storing your sounds (unless you buy a 3rd party midi controller from Microdesignum or similar), you have to dial your sounds in manually. As with all the "9" series pedals, both outputs put out dry signal with the pedal disengaged. If that doesn't suit the way you want to use the pedal, you might be lucky enough to have one with a little switch (inside the pedal casing) but otherwise you'll need a mute pedal or something to address this. Finally EHX say there's an onboard compressor but there's no way to configure it, so if you don't like what it does then you need to add another stage of compression against their advice.

I've also used the Boss SY-1, which has most of the same niggles but loads more sounds. But I still prefer the Synth9 overall because it's just so much fun!