I took a flight with Monarch Airlines back in the early 1990’s, and the aircraft was a L-1011 Tristar. I can’t recall the seating configuration, but it was one of the most comfortable and roomy aircraft I’ve ever flown on.
That said, I’m flying to Singapore on an A380 in December, so that might take first prize in the comfort stakes. I can only hope it’s better than the Cathay Pacific A340-300 I flew on a few years back, which was awful.