I don't know if there really is a preference outside of your own.
Scout has shield stuns, hunter has pet, ranger has self buffs.
I've had a ton of fun as a melee hunter on mordred, though that was a way later patch. 50sword/4x beast/3x stealth (I forget the exact numbers). The sword and shield until evade stun then swap to 2h for ragnarok was brutal.
I leveled scout to 25 with a combination of solo and group xp.
Class seemed ok. No real deal breaker issues.
After 20 tireless 1 helps a lot.
I tested hunter, cool thing about hunter is you can charm an animal or insect or use ur pet and stick it somewhere and use pet attack command while stealthed and remain stealthed. Same as uthgard for this patch level. Also, heal pet in arachite priest. Plus self buffs.
Ranger, self buffs, self da.
Again, lots of good choices. I think it all three will be viable. Scout with pots, viable.
On the other hand, ranger melee damage is on a slightly lower damage table than scouts and hunters. Bow damage is the same damage table.
I'd be tempted by the scout's shield slam, but I see nothing appealing about the hunter. The short time I spent on Midgard asking in /guild showed that it certainly wasn't a popular class among middies either.
With the archery changes back in the day, hunter was great.
I had a successful melee hunter. 50sword, 40-something beast, and 30-something stealth. Sword and small shield until you land the evade stun and swap to 2h for ragnarok back style. It was brutal. Though this was Mordred.
Hunters give up bow damage for more melee damage and a pet +self buffs/speed boost. The thing on Phoenix here, is that self buffing classes, especially soloing, will actually have an advantage against other soloers because of no buffbots.
Edit: possibly slightly longer bow range (100-200 units). Could not confirm at this patch level. Shield slam. No other utilities. They are a straight archer class.
Rangers fall in the middle of the two. Self buffs and specced for melee they can be pretty brutal if played right. Even not, they can nearly match scouts on bow damage with their self buffs.
It's a toss up really. Play whatever style might fit you.