I should note that I’ve never played the Hard difficulties.
I always play the tutorial for the purpose of leveling up some units:
Lyn: the only reason I waste my time with useless Eliwood and Lyn is so I can avoid the chapter you fight Loyd. At the end of the game, these two Lords are liabilities.
Florina: obvious reasons
Sane: my favorite of the cavaliers
Kent: I sometimes end up with a low level Kent because I prefer to feed Sane kills.
Rath: I really enjoy the versatility of the /Nomad TrooperRanger class. Also, since he’s your only primary bow user that is actually useful, I go ahead and give him the Orion’s Bolt.
Lucius: the only reason I use him is because he gets C level in staves, which makes him far better than the other non promoted magic users”
Sarra: it takes awhile, but I give a lot of experience to Sarra. It usually works out she gets to level 20 on board the pirate ship. This is convenient since this is the place to get your first Giulding Ring.
Nils: only if I’m actually willing to go to that extra chapter.