The B-17 was in fact better armed as was the B-24.
The big advantage the Lancaster had was it’s incredible for the time bomb load. It could carry 22,000 pounds. It also had a much longer range than the B-17.
I will admit that an American aircraft carrying 13 .50 caliber guns was way ahead of 10 .303 machine guns.
I know that Lancasters were still being used only a few years ago, tho not as bombers.
Let us be honest, the carpet bombing was essentially a terror tactic which failed, not a military strategic offensive as was the American precision daylight attacks against military targets. In fact the Brits opposed the American strategy, and one wonders why, given the results.
You’re probably thinking of the Avro Shackleton, which isn’t a Lancaster but rather a third or fourth generation evolution of the Lancaster, powered by Griffon engines.
They were mainly ASW/Patrol aircraft, until the Nimrod came into service. Some were used as AEW platforms into the late 1980s or early 90s, their retirement postponed by the delays and cancellation of the Nimrod AEW. They were replaced by the RAF version of the E-3 Sentry.