Good is subjective, a company that one person finds good, another could find bad.

Saying that, for the past 2 years I've used coverforyou with their travel disruption (that's the important add-on) and I'm covered for almost everything and the missed connection cover on their annual platinum is £1000.
I've had 2 claims with them, one for delayed baggage and another for a missed connection (on separate tickets) and both were ok, bit slow but they got sorted no problem.

Ultimately all you can do is google companies and read their policies carefully, probably avoid buying through a comparison site as they tend to cut certain features in order to make the price cheaper.