What card processor/online payment service to use?

Currently we only accept check or cash payments for our business. We want to expand into in person and online card payments or ACH.

What service provider/card processor should we use?
Requirements:
Able to receive card/ACH payments online
Able to process card payment in person

preferably something with good rates.
We are new to this part of the business so any help is appreciated.
Our business is a service business, few larger transactions anywhere from 75-200 transactions per month.