The key insight in what you wrote here, "(biggest client just saw our tooling stack and told us we're 10 years ahead of the ad agencies working in the same space)", is the word client.
If you are going to build your own ERP software, make sure that is the product your company is selling. The same goes for building a new 'web framework' for your web company. Never build a complex product from scratch if that isn't going to be your business. It never works out, because when you have to choose between revenue and improving something in your framework, you'll going to have to chose the former.
Years later, your company, if it is successful in doing what its supposed to do, is going to be paying big $ to retool and replace what you have built. The 2010s were the decade of teams replacing the custom shit they built in the 00s.
If you are going to build your own ERP software, make sure that is the product your company is selling. The same goes for building a new 'web framework' for your web company. Never build a complex product from scratch if that isn't going to be your business. It never works out, because when you have to choose between revenue and improving something in your framework, you'll going to have to chose the former.
Years later, your company, if it is successful in doing what its supposed to do, is going to be paying big $ to retool and replace what you have built. The 2010s were the decade of teams replacing the custom shit they built in the 00s.