My 2 cents...
I used to hate the guys that replied with this kind of comment. I was like...no crap doosh nozzle, but if I wanted to play keys I wouldn't be on TB! I want to play synth BASS, duh!
So I ignored these pretentious comments.
I bought so many synth pedals, so many pedal synth components, pitch to midi, hexaphonic pickups...and you know what? None of it was synthy enough for me. Too glitchy to be predictable (korg G5 is non glitchy), terrible tracking, notes just cutting out, horrible programming interfaces...on and on. Thousands of dollars later and I was about to start back at the beginning because maybe I wasn't using that particular pedal right last time.
Except...I turned on my dusty midi keyboard a few months ago and loaded up Massive with a bass synth. That's the sound I have been searching for forever!! Those keyboard comments were right. The crow has been eaten. On top of all that, the keyboard layout has opened me up to new note choices. Being kinda stuck in bass mode for so long, I have gotten a hair stale and predictable with note choices. But the unfamiliar KB layout has made a huge difference in creating fresh new lines. Sure I can play in a key signature, but it's the new layout. Like detuning all your strings randomly and giving it a go.
I don't wanna be that guy that says go real synth, but man it's friggin awesome. Sure some will disagree and claim pedals can do the same. Good. Have fun with them. Try holding that low E for more than 1/2 a measure. Low B? Hahahaha. Beat synced LFO's? Pitch, amp, or filter envelopes? You can be up and running like a pro for less than $200 and slay any pedal Chris Wolfen-whoever puts on his pedalboard. I have a Moog Minitaur arriving shortly. This is gonna be good.
Just saying. Rant/soapbox/high horse over.
I vote Korg G5. The MB SS is cool but a PITA to change settings. The Boss SYB-5 is ok. Never tried the Zoom stuff...just not into Zoom. There are other options of varying degrees of suck, expense, unique, but the G5 will get you going with the least frustration down the road.