Base fee plus per-employee is the formula that matters
Nearly everything here prices as a monthly platform fee plus a per-employee-per-month charge. At 5 employees the base fee dominates and the cheapest base wins; at 100 the per-employee rate dominates and a $6 difference is $7,200 a year. Calculate at your headcount 18 months out, not today's.
Decide whether you are buying payroll or an HR system
These are different products that increasingly overlap. Payroll-first tools (Gusto, Justworks) nail pay runs, tax filing and benefits. HRIS-first tools (BambooHR) nail records, onboarding, time off and performance, and bolt payroll on. Rippling attempts both plus IT. Buying an HRIS to fix payroll problems, or vice versa, produces the unhappiest reviews in this category.
A PEO is a different legal relationship
Justworks is a professional employer organization: it co-employs your staff, which is how it gets you large-group health plans a 10-person company could never access on its own. That is a real benefit and a real trade — you get less control over plan selection and switching away later means re-establishing your own insurance. Decide on the model before you compare features.
Global hiring changes the answer entirely
The moment you employ someone in another country, domestic payroll tools stop being sufficient and you need an employer of record. Deel and its peers charge a flat monthly fee per international worker that looks expensive next to a $6 per-employee HRIS — until you price out registering a legal entity abroad, which is the actual alternative.