I most definitely prefer the well-trained and highly-skilled from 1st-level idea. In my mind, the PC's are NOT average people. Average people, even with the same amount of training, couldn't equal a PC in terms of raw power. And on top of that, I feel that to even GET that training, a person has to distinguish themselves as being above average.
So I work off the assumption that whatever class the PC might be, they have been training for along time just to get to 1st-level.
Precisely my assumption. Some brief 1st level backgrounds for the PC's in my campaigns
-- Second son of a noble, trained in wizardy and law by his childless (gay) wizard uncle.
-- Militia sergeant in a Furyondian lord's army on the Veng River, fighting the orcs of Iuz. Had to flee because he seduced his lord's daughter!
-- Wandering cleric of St. Cuthbert
-- Monk of Rao. Was trying to loot the Lost Caverns of Tsojcanth 100 years ago. Was turned to stone, rest of party is long dead. Rescued by a party with Stone to Flesh.
-- Scout from a hidden city of a fallen civilization. Well trained Ranger, but doesn't speak the local language.
-- Half-elf druid who is coming of age and must do "walkabout" to become an adult, raised by adventurer father.
-- Elf whose father is in a secret society. Wants to aid the humans in the war with Iuz, and prove his worthiness to the secret society to join it.
-- Elf merchant who was attacked by goblins and decided to become an adventurer.
-- Militia sergeant in a small town, also worked a river fisherman. Joined the party when they came through town, on the advice of his lord, who saw his potential and gave him arms and armor.
-- Dwarvish wizard who trained for many years. Kicked out by his people when he saved his Elvish thief friend, who was caught trying to loot the dwarves treasury
-- The elf thief
So yes, the folks are not yet heroes, by any means, but they are also not raw recruits.
Equivalent in the modern world to a college graduate with a year or two of very junior experience, ready to do some things for themselves.
Or a soldier with not just boot camp, but a tour of duty -- not Rambo, but not Gomer Pyle either -- and potential to be Rambo. Think of the guys in "Saving Private Ryan" -- well-trained, elite Rangers who have already fought in Africa, but are going to achieve glory in Normandy.