Day of The Tentacle is the best for me and it's also the classic that has aged the better with its cartoony graphics.
But point&click games seem to regain some popularity on PC now with Broken Sword 4, Runaway 2, Sam & Max Season 1 that are quite good. (BS4 might be budget in your area)
Even better games are expected in 2008 but the one that stands out for me is A Vampyre Story