I am in the boat to suggest getting a proper MIDI controller and a DAW with VSTi's, or keys with their own synth software. By the time the guitar signal is synthesized and comes out the guitar amp, you are likely not going to have a convincing synthesizer sound. Or maybe that is what you are going for. If you run the synthesized signal out direct to PA or otherwise avoid the guitar amp, that is smart- although again at that point you could run a traditional synth setup easier methinks. If you are looking for a blend between your guitar and synth, then of course you will need a dedicated "guitar synth" pedal.

But to answer the question, I think the two top units are the Roland GR-55 (With GK pickup) and the BOSS SY-300. However, this is talking about the more "pristine" synth sounds that are controlled by MIDI signals (or as close as you can get to MIDI with a guitar signal), instead of the sounds that just come from heavily modifying the guitar tone. If the latter, that is a whole different animal. POGs, Bitcrushers, Stutter-ers, etc...
Last edited by Will Lane at Oct 24, 2016,
Well, as a synth player for over 20 years, the top today is the Fishman Triple Play with VSIs of your choice. Roland hasn't put out a midi/sample based synth system in many years.
Dave @ Seymour Duncan
I though Roland just rolled new line with the release of Gt-100, about 3 years or so?

Basically, it's this...

Joined new band and need to beef up a few parts that could use me going on a tangent and the other guy playing the guitar parts. There are a few Celtic and Scottish elements there that would be cool to enhance with say bagpipes or something...I don't want to get too gear crazy but something that would be easy to setup through my current gear.
I'm using a modular system so I can just go into the power amp, but it has to go through guitar speakers, at least for rehearsals, live I can feed it direct.

... And no, I'm talking real synths, not the tone bender devices.

How about pc controlled stuff? I coukd just get guitar midi pickup and use my orchestral synth vsts? That'll be nice, just don't know patch changes will happen as I have IK Miroslav Philharmonic, Moog and other vsts...I also have old Roland midi brain but can't play piano for sh*t, so I could interface guitar into that and be productive.
If you are gonna use VSTis, go for the Triple Play. The Roland synth they put out a few years ago isn't triggering samples, it is more like an actual synthesizer.
Dave @ Seymour Duncan
I remember the ancient Roland I used back in the day had midi out and triggered keyboard modules, tracking was awful.
How about software, how to get around on the pc side? So far I've considered this part kid's toys and haven't investigated it for performance as I felt wasn't solid enough, but maybe taking a portable laptop (have a $250 solid drive cheapie) + extra midi controller might just do it.
For software, the Triple Play comes with the PC software. It is just an interface to load VSTi's into, and you get to set the string sensitivity, etc. I don't own a Triple Play, but have used it, and it is miles better than any Roland.
Dave @ Seymour Duncan