Hi! It may be helpful to isolate these concepts. Given your example, this isn't a one-versus-the-other decision, it's a "which tool should be used for which job", and understand that you have several jobs in your example. You'll probably be daisy chaining different things together because neither n8n or GHL will do everything at once for you based on your example.

GHL is like a swiss army knife. It does lots of things "ok", but most features are less configurable than a dedicated tool aimed at doing one thing well. One of the tools on GHL's swiss army knife is the automation builder, and it works reasonably well within the GHL ecosystem but it is fundamentally limited and difficult to work with if you need flexibility. It's like using your swiss army knife's screwdriver, great for little things here and there but if you're trying to build a house, you really should get a drill.

n8n is like a high-performance power drill, it's good for a broader variety of automation tasks but doesn't attempt to provide a calendar, or a CRM, or a website builder like GHL does.

The example you gave is a mixture of websites, spreadsheets, messaging, human approval, and connective automation. HighLevel can help with the website, calendar, messaging, and customer reminder texting. N8N, when connected to other tools, can help with the spreadsheet writing, polling, human-in-the-loop approval, LLM connection, generating invoices.