For most small businesses the honest answer is: WordPress if you need a content site you can edit yourself, Shopify if selling is the whole business and you want somebody else to run the plumbing, and custom if what you actually need is software rather than a website. Most people asking this question need one of the first two.
The reason it feels harder than that is that everyone answering has a stake in the answer. A WordPress shop recommends WordPress. A Shopify partner recommends Shopify. I build all three, so what follows is what each one is genuinely good at and where each one hurts.
WordPress
What it is good at. Content. If your business wins by publishing things, explaining things, and ranking for what you explain, WordPress is still the most direct path. You can edit pages yourself without calling anyone, there is a plugin for almost everything, and every developer on earth has seen it before, so you are never trapped with one person.
Where it hurts. Plugins are the whole bargain. Every one you add is code from a stranger running on your site, and each is a maintenance obligation and a potential security hole. Sites that nobody maintains break slowly and quietly, usually in the contact form. That is not a WordPress flaw exactly, but it is a WordPress reality, and it is why a care plan is not optional on a WordPress site the way it might be elsewhere.
Who it suits. A business with something to say, a need to edit its own pages, and either the discipline or the plan to keep it updated.
Shopify
What it is good at. Selling. The checkout works, payments work, taxes and shipping are handled, and the infrastructure is somebody else's problem. For a straightforward product business, the speed to a working store is genuinely hard to beat.
Where it hurts. You are renting the rules. The monthly fee is the smallest part; transaction costs, app subscriptions, and theme limits add up, and every app is another recurring line. When you need behaviour the platform does not support, you do not negotiate with it, you work around it. And some product categories simply are not welcome, which you usually discover late.
Who it suits. A business whose main job is selling reasonably standard products, that values speed and stability over control.
Custom
What it is good at. Doing exactly what you need. No platform tax, no fighting someone else's assumptions, no app subscription for behaviour that should have been built in. It is also the only option when the thing you need is not really a website.
Where it hurts. It costs more up front and it needs someone who knows it. That is a real risk and you should treat it as one. My answer is that you own the code and the accounts, so you can hand it to another developer, but you should still ask anyone proposing custom work what happens if they disappear.
Who it suits. Businesses with a workflow that genuinely does not fit the shelf. Approval-gated stores, unusual quoting, internal operations, anything regulated.
The case where the shelf does not fit
Picture a store that looks normal and is not. Age verification has to happen before any content is shown. Access has to be earned through an application with manual approval rather than an instant signup. The whole thing has to run in English and Spanish. And it sells in a category standard payment processors decline, so the gateway integration has to be custom.
You can push a platform toward some of that with apps. You end up with five subscriptions, a fragile chain of plugins, and behaviour that breaks whenever one of them updates. At some point paying for the thing you actually need is cheaper than renting four things that nearly do it.
That is the real test. Not "is custom better", but "how many workarounds am I stacking before the workaround is the product".
What this costs
On my price list, a small business website starts at $2,900 and an ecommerce build starts at $4,800, on whichever platform fits. Custom applications and dashboards start at $9,500 and are always quoted after discovery rather than from a price list.
Platform costs stay in your own accounts either way. Shopify's monthly fee, WordPress plugin licenses, payment processing: those are yours, billed to you directly, and I do not mark them up. Ask anyone quoting you whether they do.
Care plans start at $65 a month and matter most on WordPress, for the reasons above.
The switching costs nobody mentions
Every one of these decisions is reversible and none of them is cheap to reverse.
Moving platforms means your content moves, your URLs change, and if the redirects are done badly you lose search rankings you spent years earning. Your product data has to be exported and reshaped. Your customer accounts usually do not come with you at all. Your integrations get rebuilt.
None of that is a reason to stay somewhere wrong. It is a reason to take the first decision seriously, and a reason to be suspicious of anyone who tells you migrating is simple.
How I would actually decide
Ask what your business wins on.
If you win by being findable and explaining things well, you need a content site, and WordPress is a reasonable default.
If you win by selling products efficiently and you do not have unusual requirements, Shopify will get you there fastest and the platform fee is rent you are happy to pay.
If you win because your operation does something specific that off-the-shelf software fights you on, stop looking at website platforms. You need software, and that is the apps and dashboards conversation.
And if you are not sure, say so out loud to whoever you are talking to. The answer you get tells you a great deal about whether they are solving your problem or selling their preference.
If you want to talk it through, the ecommerce page covers how a store build runs, and everything is priced on the pricing page.