That's a hard one. I generally like humour best. The funniest book ever written is Three Men in a Boat by Jerome K Jerome but he was hardly a prolific writer.
P G Wodehouse was outstanding (even if somewhat formulaic), with any of the 'Jeeves' series to be commended.
Alan Coren was possibly the best writer of the 20th century though, through his columns in Punch. ("The Hangover in Question" was brilliant).
For anyone with an interest in law, A P Herbert's 'Uncommon Law' (and 'More Uncommon Law') is brilliantly constructed, and incredibly funny!
Since you mention D H Lawrence, I love his poetry rather than his novels. Here's my favourite:
""How can I teach you when your blue
Eyes look at me so?
Your deep bewilderment filters through
My mind, and I know
That I put to flight from out of you
Rare birds that no
Enticing will recall; when I
Do watch your eyes,
Wherein the timid wonders fly
Off in surprise,
Then, oh, I do forget all my
Enterprise,
And all the lessons let slip by:
For you are wise"
Chris