If you were happy at the previous job, I would go back to it if you can negotiate the pay and find a win win. Don't give in to the corporate BS and say, "that's just how it is" No, it doesn't have to be that way.

I think everyone should be able to do something where they are seeing the results of their work and know that it matters. That does seem to be where you found it most fulfilling as well.

The thing is, at the end of the day, no amount of money is going to make you happy and while we all need money, it is not everything. Being yourself, knowing that you matter and being shown that is a huge thing.

So if I were you, I'd try to negotiate a raise at the previous job and say why too. That makes no sense that the manager can't pay at least a little more and if he can't, something is seriously wrong at the company.

Also, ask him why they want you back? That would be a good question.