This is one of those situations where there isn't a single "better" option—it depends on your working relationship with the US client.
If you're genuinely operating independently (you control your work, can have multiple clients, invoice for your services, etc.), then working as an independent contractor is often simpler and can be more tax-efficient. However, you need to make sure the relationship actually meets the Canadian tests for independent contractor status, as misclassification can create tax and employment law issues for both you and the client.
An Employer of Record (EOR) is usually the safer option if your US client wants to treat you like a regular employee but doesn't have a Canadian entity. The EOR handles Canadian payroll, tax withholdings, CPP/EI, and employment law compliance, although it generally comes at a higher cost.
Given that you're relocating to Canada as a PR while continuing to work for a US-based client, I'd strongly recommend getting advice from a cross-border tax professional before deciding. The structure can affect your Canadian tax obligations, your client's compliance responsibilities, and how the agreement should be drafted.
For Ontario, you may want to speak with firms that regularly handle cross-border employment and tax matters. Some options include Hanson Crossborder Tax Professional Corporation, US Taxes Toronto - Cross Border Tax Preparers, and for the employment law side, firms such as Monkhouse Law or Wong Employment Law are worth considering.
I'd make sure whoever you hire has experience with both Canadian tax and cross-border employment, since this type of arrangement often requires coordinated legal and accounting advice rather than just one or the other.
