I'll start things off.
Arcane Trickster
Change the requirements to Sneak Attack 1d6, 1st level spells + mage hand, 5 ranks Spellcraft and Stealth.
Change base attack progression from half to 3/4.
Change spellcasting to 3/4 (as arcane archer or dragon disciple).
Change sneak attack to 3/4 (as master spy).
Shadowdancer
Give them sneak attack every 3 levels, possibly replacing rogue talents (or giving them a choice between the two).
Assassin
Change Death Attack to full-round action (with no setup time) which improves to standard action when Swift Death is acquired.
Duelist
Allow them to add Dex modifier to damage instead of Str when wielding one handed piercing or light weapon.
Pathfinder Chronicler
Give them 3/4 spell progression, at the very least.
For Arcane Trickster, I would add something to the effect that your AT levels are counted as Rogue levels for the purpose of qualifying for Advanced Rogue Talents rather like the the way an Eldritch Knights levels count as fighter levels for qualifying for feats. That way a Rogue 4 / Arcane Trickster 6 who takes additional levels of Rogue can choose Advanced Rogue Talents.