Armor choice for nimble is definitely more complex than just picking 300/300 with fur padding for battleforged.
Here are some standard nimble armor options that are efficient and don't require named armor or rare enemy drops (see assassin's robe).

A)
-Armor: sallet, Southern mail shirt (FAT -16).
-Attachment: hyena pelt.
Total: 120/125, Nimble 41%, INI +15.
B)
-Armor: sallet, padded leather/stitched nomad armour (FAT -13).
-Attachment: bone plate (FAT -2).
Total: 120/80, Nimble 40%.
C)
-Armor: sallet, linothorax (FAT -12).
-Attachment: lindwurm scale cloak (FAT -3).
Total: 120/135, Nimble 40%.
D)
-Armor: barbute, gambeson (FAT -15).
-Attachment: hyena pelt.
Total: 190/80, Nimble 40%, INI +15.
E)
-Armor: barbute, padded surcoat (FAT -13).
-Attachment: bone plate (FAT -2).
Total: 190/50, Nimble 40%.
F)
-Armor: barbute, padded surcoat (FAT -13).
-Attachment: lindwurm scale cloak (FAT -3).
Total: 190/110, Nimble 41%.

A is the most accessible since it doesn't require you to buy an expensive barbute or fight unholds/lindwurms. Plus you might want to save those good attachments for named armor. I didn't even bother mentioning the best nimble attachment, the kraken horn plate, since you would never put that on regular armor.
E is probably the best one overall against hard hitting enemies.