My favourite period is probably the cluster of films he did from the early '80's , namely
Zelig, Broadway Danny Rose, Purple Rose Of Cairo, Hannah & Her Sisters and Radio Days. Of the early period it has to be Annie Hall and Manhattan.
Of his late period films, I thought the first two of the 'British Trilogy' ie Match Point and Scoop were a low point but thankfully the recent You Will Meet A Tall Dark Stranger is much better. Sweet & Lowdown was great, as was Husbands & Wives,and Everyone Says I Love You.I loved Whatever Works and was surprised at the many negative reviews it received. Just goes to show what a subjective thing humour is.
I personally couldn't care less about his personal life.