There's no equivalent to MCC in Google analytics. You must link each adWords account individually to each analytics profile you want.
If the client doesn't have a Google it's their responsability to get one. And you should assign their Google Account as an Administrator for the Google Analytics Account.
Create one Google Analytics Account to each profile, but only if they don't already have one. If they already have a Google Analytics account ask for Administrator access on you Google Account.
Create a Google Account to be set as Administrator to all clients account. Be sure to take care of this account, and if someone who has access to this account leaves the agency you MUST reset the password. Make sure you really need Administrator access, and acknowledge that it comes with responsibilities. If you don't need just ask for User access. Notice that some users won't be willing to handle you any of these accesses types. It's completely fine and they are on their right if they have strong privacy policies and don't trust their data to your agency.
NEVER delete an account. If you are not in a contract with a client anymore their data will be showing on your GA Account until another Administrator revokes your access. If you have a couple of these accounts and want to "cleanup" you profile lists ask the customer to revoke your access. If you delete an account you're not deleting just for yourself but for anyone that has access to this account. This data is also not recoverable, so it's lost forever.
Yes this means you'll have more work managing filters for these clients. But this is the only sane way to manage Google Analytics for multiple clients professionally. You can use GA Copy & Paste to help you managing these filters on different accounts.
It's good to notice the difference between a Google Account and a Google Analytics Account.
- Google Account handles authorization and authentication for various google services. A gmail account is automatically a Google account. Other emails could also be transformed into Google Accounts. Any Google Apps email is automatically a Google Account.
- A Google Analytics Account is just a collection of one or more Web Properties.
- Web Properties are the UA numbers you see on ga (UA-XXXXX-X), all data you send to GA is assigned to one WP. WP also serves as containers for Google Analytics Profiles