I used to utilize Stripe.
Not anymore, for reasons I won't get into.
For my clients I utilize Braintree Payments. Best processing company on the web. Outside of them I use a CC processor here in Camarillo where i live. They've gotta deal with Authorize.net and can offer processing for 1.9% + $40 a month. Bank Card USA is the name of the company. If you're moving a lot of volume then a small business CC processor will be your best bet.
As far as security, all of the processors are pretty secure, just don't be an idiot and not research the companies.