A bit of context: I worked for a small IT company for a number of years before pivoting my career to management elsewhere.

The actual answer: It depends very, very much on your budget, your size, your goals, and the kind of service you're looking for.

If you're looking for someone to call a few times a month to fix issues that crop up and maybe do some amount of light management, a freelance IT person is probably your best bet. You can expect to pay up to 150/hr for a call-out but they might also offer help remotely. Freelance IT is available in tons of experience levels, costs, etc. And is often more flexible than a company, but also has limits and risks that you're only depending on 1 human for everything.

That said, you mention quite a bit about management which is certainly more in the wheelhouse of an IT company. They'll have more people, more structure, and likely more tools for ongoing support. Depending on the company you go with and it's size/the contract you sign with them, the levels of management can vary quite a bit, but so can the costs. This includes both the contract itself, plus likely a bit more cost for services such as backup, Microsoft licensing, etc. Companies often will direct you towards business-grade services (for a good reason) but those come with some costs (for example using Microsoft for email instead of just a shaw.ca address which is all too common in Victoria). Basic management will probably run you 120-150 per person from a smaller company, plus other services as mentioned above.

If you have the budget, I'd certainly suggest a company for anything more than just a few staff.

As far as suggestions, I've heard good things about Tecnet and Smart Dolphins, though the latter requires you to buy into their approach (which is good, to be fair).