Kashflow in the UK is good. Xero is another to look at. But only if your accountant is using them.
Do. Not. Be. Your. Own. Accountant.
Also, if you have any outside Investors they will want clean financials. QB operated by an acccountant. If you hope to bring in Investors later and you have shit financial records -- or just amateur hour financial records -- the natural thought in Mr. Wallet's brain is "They can't handle their own money, why should I give them mine?"
All comments above learned the hard way, via pain. :-)
I have no particular love for Intuit. QB is the Windows of small accounting systems. The Mac version is the despised bastard offspring despised and ignored by it's mother. But until you're bigger or until a plausible alternative arrives, use it.
I think the break-point will be at a couple of million of revenue. Above that and growing? Migrate to an industrial-strength package with dedicates bookkeeping people in house.
To put it another way, these "accounting" packages are more about book-keeping and report generating - all useful, but no substitute for the advice from a human accountant who can advise about tax-efficient structures for your particular circumstances.
(I'm not affiliated, just a happy user)