I hate to say it, and sorry to be controversial, but none of the RAF's retired types were really world beating either by the time they were retired or even when introduced. The Eurofighter Typhoon is OK, as was the Lightning. Tornado, adequate. We'd have bene far better to buy a half dozen squadrons of F/A18s and upgraded to E/F models really. Could have deployed them on a carrier, and on land. A truly versatile aircraft. F15s are still better than the Eurofighter and they're 40 years old.
The Harrier was different, unique and specialised like nothing before or since. The Harrier II was a fine aircraft, once the wiring fires were sorted. But other than cost, we could have bought some A10s and had a far more potent beast.
Hate to say it, and credit where it's due, but the UK military industry really hasn't done something world leading since the Spitfire. Hope BAe's new baby kicks ass though!