Lucky Jim is still my favorite. I've always liked Amis pere better than fils. It's a brilliant comic novel.
Of all those writers, my favorite remains Evelyn Waugh, although his first books go back earlier than the others. Decline and Fall, Vile Bodies, A Handful of Dust, The Loved One, and most especially Brideshead Revisited. Anyone who saw the TV series of Brideshead should read the book, which is one of the major works of the twentieth century, IMHO. The Oxford part, which dominates the TV series, is only a small part of the whole book.
Also of intererest are Waugh's trilogy, Sword of Honour, set in the Second World War. The books are Men at Arms (1952), Officers and Gentlemen (1955) and Unconditional Surrender (1961). They reflect some of Waugh's own experiences during the war, including time spent in Yugoslavia under Tito, and the military activities of some of his friends. It's a brilliant picture of the heroism and the compromises of that war--notably the compromises that came from allying ourselves with the likes of Stalin and Tito in the war against Hitler.
Some critics think it's Waugh's greatest work, but needless to say it doesn't please most critics because of it's anti-Communist, and the great majority of literary critics remain leftists. It's a wonder they can stand Waugh at all, but he's too brilliant and penetrating to ignore.