I use GoCardless as a merchant to receive recurring payments. It works well once it's set up, fees are cheaper than card payments. Payout times are relatively slow at 1-2 weeks depending on where weekends fall; that's fine if you can run your business from working capital while waiting for DD payments to turn up. May be trickier if your cashflow needs require the money in hand quickly, though.
If you do lots of transactions they now have a Pro product which gives you much greater control over the payment process.
I've not used anybody else so that's just an anecdote, but it's a start!