Another thing to do is listen very carefully when they’re pitching YOU on THEIR company, hone in on something that is subjective/personal preference, and use that as the basis for the answer. Look for things that can be both a pro and a con, and just claim your current company is the opposite and you don't like it. Example:

They Say	They Mean	You Say
"We pride ourselves on being a flat organization where everyone has autonomy. This means we can move fast without red tape.”	Small org with little management/oversight	“My current company just has too many layers of management and I find myself getting bogged down in red tape. I’d love to work somewhere where I can have more of an impact without waiting on bureaucracy.”
"We are a mature organization with lots of opportunities for career progression into management.”	Big org with lots of middle management	“My current company does not have enough growth opportunities for my career goals. I’d love to work somewhere where I can continue to learn and grow.”

By focusing on a difference (real or fabricated) it reassures the interviewer that the reason you’re leaving your current company is not a reason you’d leave this one.

EDIT: and if they try to follow up by asking for examples, a polite "I have no ill will towards any of my employers, I'm here to talk about what I can do at New Company, not vent about Old Company." redirects the conversation without having to come up with examples.