Best for a first rollout of one to three apps.
Best once you're live and iterating.
Best if you're already on Odoo or another system.
One app (say, CRM) is a different job than five apps talking to each other.
A clean spreadsheet migrates in a day. Ten years of inconsistent records takes longer.
Standard configuration is fast. A bespoke module against an unusual workflow isn't.
Odoo alone is simpler to price than Odoo wired into three other systems.