Agreed. 'Welcome to The Hellmouth' and 'City Of...' are the two best openers of each show, which set the coda for the series.
To be honest, a lot of opening Buffy eps are very weak. 'When She Was Bad', 'Anne' and 'The Freshman' are all really uneven. Although I like the 'Bargaining' 2-parter and 'Lessons'.
All of Angel's opening eps are very strong. 'Judgement', 'Heartthrob', 'Deep Down' and 'Conviction' all manage to be good stories while setting the tone for the coming season- redemption, romance, father/son relationships, the battle with W&H. All really good quality. 🙂