My favourite is April. Spring is properly established (Beasts from the East notwithstanding), the days are noticeably longer and brighter, daffodils and tree blossom abound, it's often when Easter falls and there's the promise of May and June to come.
Conversely, November is just miserable. Increasingly darker days, chilly, bare trees, the smell of decay from rotting leaves and flowers, mud. Yuck. Nothing good about November at all.
Obviously, folk in the southern hemisphere may disagree !