ADP is a widely-trusted payroll solution that also offers many other HR tools if you need them. Their expertise is a good fit at SMBs but also enterprises.
ADP is perhaps the best known company in the payroll space. Given their scale, they can offer just about everything your business needs when it comes to payroll and benefits.
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ADP offers in-depth implementation guides on their resources page. Since you're looking for a payroll solution, you might want to look at this document if you're considering them.
ADP has a customer success department. For payroll matters, they also offer accounting and tax expert support if you need it.
Sometimes ADP has special offers, like getting 3 months free when you sign up for their small business payroll processing plan. However, they don't share the prices for their payroll packages, so you'd have to request a quote to move forward.