As has been FT advice for eons, only you can determine value of your time and money.

If the bonus Tier points are most important, then add a connection on the east coast (with the stop at LHR).

Then your decision is (assuming flight times are close) the worth of $300 extra on the JFK connection, which gets you better lounges and much better planes (on both LHR-JFK and JFK-LAX) than the CLT connection.