If they were both on the table, it would be easy.
But: I have committed to BigGlobalCorp, and as a rule I don't go back on my word, despite the fact they would have no qualms doing so. They pay more, but are harder to get to. I'm not really a fan of BigCorps but the team seem more like me despite being within such an organisation. Job#1 has much more exciting tech, and is more ethically sound, but I've only met the hiring manager.
I've not responded yet, the plan at the moment is to turn up tomorrow and see how it pans out (I won't be 100% convinced it exists until I've got my Brompton under the desk) and let Job#1 know by the end of the day.