which is the best cms for landing pages?

Take or watch the Track on PHP Development. Pay close attention in the Database Foundations and the PDO Data Objects, then do the Following:

1. Gather all Data Common to customers.
2. Store that common data in a proprietary database(i.e your company database)
3. Build a PDO based page, using Prepared Queries.
4. Build only one Landing page, one Form Submission Page and other pages.
5. Escape the output to the browser, in the particular places needed.
6. All customers will see a professionally done page, outputting the data they supplied.

The only issue here is that the Prepared queries cannot output Customer ID's in the argument passing, ie:

index.php?id=nnn

because you don't want customer n=1 to look at customer n=400's page. To fix that, obfuscate the customer's id in the prepared query like so:

SELECT id, name, column1, market_type,other_columns FROM customer
WHERE id=nnn AND market_type='healthcare'

then pass the name as the Page argument, like so: (Yes nnn=id, but the Prepared statement is passed to server-side PHP, so code inspectors like me, will never realize you are supporting multiple customers, because they wont know that the prepared statement doesn't match by name.)

index.php?name=ACME

This will hide the customers from each other unless customer ACME knows customer ACME1 is using you as a Solution Provider, but they still will not know each others customer ID. If a visitor passes foo to name, he'll recieve an SQL error at which point PHP should die().

This approach gives up creative Flexibility, but makes Management Easier, and eliminates the need for a CMS all together

Wow thank you