I personally prefer Adamant for Arcanine because while 110 attack is good, it's not off the charts and I like to have the extra power. Jolly variants aren't used as much, but they work fine, and let's it outspeed + nature base 90 and 85's notably.
This moveset would be the one I would use for Jolly or Adamant.
Arcanine @ Life Orb / Leftovers
Ability: Flash Fire / Intimidate
EVs: 4 HP/ 252 Atk / 252 Spd
Jolly / Adamant Nature
- Flare Blitz
- Extreme Speed
- Close Combat
- Wild Charge / Morning Sun