*under Edit*
Thief
All Rogues are masters of stealth and want to make sure they prioritize Dexterity. This helps them disappear when they want to, and as long as you are using ranged weapons, or melee weapons with the "Finesse" property, you can add your Dexterity to all of your attack actions. Since Rogues tend to work outside the traditional confines of the law, you should definitely use Charisma as your next priority. If your Thief is caught by the city guard doing something illicit, you might need to deceive them in order to avoid jail time.
For a Thief, It is wise to prioritize Strength as a top 3 statistic because there is a very good chance that you are going to be doing a lot of climbing to 2nd and 3rd floor balconies. I also feel that this sentence from the rulebook under Athletics describes a situation you may find yourself in, more often than you would like, "You attempt to...cling to a surface while someone is trying to knock you off."
Assassin
Assassins share some commonalities with Thieves. You want to make sure your top two abilities are Dexterity for your sneaking and stabbing, and Charisma. Assassins get a lot of incredible roleplay abilities that all focus on their ability to impersonate people, all in the name of getting close to their target. A low charisma can blow your cover and lead to all sorts of uncomfortable situations (like jail). Unlike Thieves, your 3rd ability should be Wisdom. Wisdom gives you a high Perception and Insight so you can tell if people are believing you, and pick up on guards trying to surround you before it becomes a problem.
Arcane Trickster
Arcane Trickster's are Rogues who have trained in magic that can help them with their...extra-curricular activities. They use Intelligence as a spellcasting statistic and as such, this should be your second priority (behind Dexterity). Hilariously, Arcane Tricksters are able to pickpocket with their Mage Hand cantrip and this tends to put them a bit further from the scene of a crime, making Charisma less of a priority.
