Sword & Wizardry Complete (S&W) is an early 2nd generation clone (before a lot of the 1st generation clones were out, even). It is NOT, under any circumstance, a faithful retelling of Original D&D. S&W White Box is in the same vein.
So nostalgia has an interesting place in the OSR. I've called it a cancer, but S&W shows it can be something better - an impetus for design goals an philosophy. Not by slavishly recreating old editions' rules, no (that's the cancer I mentioned earlier). By designing the game the way you played it or hazily remember playing it and doing course corrections where you see them. How to get to that good play experience is simply only using the rules you remember that were fun. S&W is probably the only OSR that properly does this.
As the king of the OSR I'm often asked which is the best clone and my answer without hesitation is Swords & Wizardry Complete*. And It's not even close. OSE is the one every talks about right now, it's quite literally bursting with unnecessary filler and a slick layout. It's Digest size because it couldn't maintain it's layout as a full-size book. OSE is what people who started D&D with 5E and first get into the OSR in 2017 or later think is the best clone. All other clones are generally less played, less read, and simply less than S&W. OSE is less than S&W because there's no design work AT ALL in OSE. As soon as the guy who threw together OSE put a hand in design, it was shown that he's obviously not a good game designer, merely a passable layout artist.
When I populated RPGnet back in the beginnings of the OSR, there was a joke that when it came to D&D clones, it's all subjective but S&W is the best one. That's very much still true all these years later with White Hack, Black Hack, Index Card Hack, Blueholme, Dark Dungeons, and 40,000 others flooding the market. S&W Complete still stands head and shoulders above the competition for a few reasons:
The game was written with love. But not a teenage love. A thirty-year-old love, and it comes through in the writing. It's a profound exercise in saying what it needs to say in 134 pages. When I saw S&W Light come out, my immediate response was "What are you retarded? Complete is only 134 pages!" And I stand by that immediate gut reaction. S&W Light is retarded. Or rather it's written for children, I suppose. It should have an age maximum on the cover of 12 years.
Intelligence in design is very understated in S&W. Example: All specialty classes are Human-Only. Assassins, Druids, Monks, Paladins, Rangers, all Human Only. Hell Clerics are Human and Half-Elf only. It actually tells you this in the Human race entry - play one of these cool classes if you're going Human. Human Fighter is a trap option for people who don't notice this. The Fighter's only saving grace mostly kicks in if the character has a high Strength, so if you didn't roll well on that stat, play a Human and pick Ranger or Paladin instead of Fighter. In the S&W Thieves and Fighters kinda suck, the reason is you should be a demi-human, with cool demi-human abilities, if you're playing one of those classes. There's an anti-Race as Class vibe throughout, the options are as follows (including best options and trap options):
Best Options:
Dwarf Fighter/Thief - Limited to 6th Level Fighter
Elf Fighter/Magic-User/Thief - Limited to 4-6 Level Fighter/8-9 Level Magic-User
Half-Elf Fighter/Magic-User/Cleric - Limited to 6-8/6-8/4
Halfling Thief
Human - All Middling Options are Best Options, dependent upon ability scores
Trap Options:
Dwarf Fighter - Limited to 6-8th Level
Elf Magic-User - Spellcasting soft-capped at 11th level
Half-Elf Cleric - 4th level max
Half-Elf Fighter - Limited to 6-8th Level
Half-Elf Magic-User - Limited to 6-8th Level
Halfling Fighter - 4th level max.
Human Fighter - Unless you have high Str/Dex
Human Thief - All Demi-humans can advance forever as Thieves
Middling Options:
Dwarf Thief
Elf Fighter
Elf Thief
Half-Elf Thief
Human Assassin
Human Cleric
Human Druid
Human Magic-User
Human Monk
Human Paladin
Human Ranger
Full List:
Dwarf Fighter - Trap Option: Limited to 6-8th Level
Dwarf Fighter/Cleric - OPTIONAL - Limited to 6th/7th level
Dwarf Fighter/Thief - Best Dwarf Option: Limited to 6th Level Fighter
Dwarf Thief
Elf Fighter
Elf Fighter/Magic-User - Limited to 4-6/8-9
Elf Fighter/Magic-User/Thief - Best Elf Option: Limited to 4-6 Level Fighter/8-9 Level Magic-User
Elf Magic-User - Trap Option: Spellcasting soft-capped at 11th level
Elf Thief
Half-Elf Cleric - Trap Option: 4th level max
Half-Elf Fighter - Trap Option: Limited to 6-8th Level
Half-Elf Fighter/Magic-User - Limited to 6-8/6-8 Level
Half-Elf Fighter/Magic-User/Cleric - Best Half-Elf Option: Limited to 6-8/6-8/4
Half-Elf Magic-User - Trap Option: Limited to 6-8th Level
Half-Elf Thief
Halfling Fighter - Trap Option: 4th level max.
Halfling Thief - Best Halfling Option
Human Assassin
Human Cleric
Human Druid
Human Fighter - Trap Option: Unless you have high Str/Dex
Human Magic-User
Human Monk
Human Paladin
Human Ranger
Human Thief - Trap Option: All Demi-humans can advance forever as Thieves
S&W outlasted Labyrinth Lord, I don't see OSE outlasting it either. Well, as long as FGG doesn't bank on that terrible boxed set they put out and keep producing the Complete book.
*S&W Complete 2nd printing, the blue devil cover painted by the legend Erol Otus to be precise.