Pharoah Trim is obviously the best choice for Furfrou, sporting an outstandingly regal cut that brings out its royal blood. Pairing this form with Cofagrigus is a must.
Pharoah is easily the rarest trim.
If you want to unlock the premium styles (La Reine, Kabuki, and Pharaoh) you must have them groom your Furfrou at least once with the Heart Trim, Diamond Trim, and the Star Trim, then the next time you talk to the clerk, you will have unlocked the following styles: La Reine, Kabuki, and Pharaoh.
Furfrou's has 2387 max CP (at Level 50). A Furfrou obtained from Raids can be encountered from 1141 CP to 1206 CP, or if weather boosted, in the 1427 CP to 1508 CP range. In Field and Special Research, Furfrou can be found in the 856 CP to 905 CP range.
Furfrou is a highly valued Pokémon and especially sought after in Pokémon HOME. It is very common to see users willing to trade Legendary Pokémon and Shinys for a Furfrou with hard-to-get trims like Pharoah. These styles can only be obtained by using the Change Form option within the Pokémon's details menu.
Pokemon GO: How To Get Heart Furfrou Tap on Furfrou's summary in the Pokemon Storage. Tap the Change Form button, and a new list with available options emerges. There are multiple Trims, but one must navigate to the Heart Furfrou. Changing Furfrou's trims in Pokemon GO costs 25 Candy and 10000 Stardust.
Pharoah Trim is Furfrou's rarest form, as it's exclusive to Egypt. Heart Trim Furfrou is also pretty rare since it can only be obtained during specific events, though when those events are active, it's easily obtainable and accessible to players worldwide.
None of these Form Changes do anything to the move sets available to Furfrou. They don't at launch, that is to say. There may be a point in the future when Furfrou's moves can change based on appearance, but for now and through the foreseeable future, they'll remain independent of one another.
Pharoah is easily the rarest trim.