I think this is my Thought to best to worst to cyl unit
Before i start of course all of them are really Great unit so i compare them in their in field and neutral stats of course.
1)lyn is arguably the best/most wanted due being the First horse Archer with incredible stats spread similar to bridelia with -2 Attack but a lot of res to Battle mage thank to her weapon,She dosen't get countered by distant counter unit and having access to horse buff + amaizing start skill kit you almost do not even Need to si outside brave bow and perhaps luna for brave bow build and of course and assist. Keep in mind that give her brave bow and eventually desperation you would delete what gives her unique ,especially not get countered Hector,ike,nowi,xander,Ryoma which are Pretty popular and most important by giving her brave bow She would lose 8speed and can't counter blade tome users still she would reach 40 speed which is good on her own with horse buff. Her bst is the highest among ranged units (outside Faye but She is a villager)
2)brave lucina is basically herself with lance and very good def which get higher thanks to her weapon. She is the spur lady from distance focused on adding +6 Speed +3 Attack during combact to allies within 2 spaces which is amaizing also It dosen't get affected by panic ploy. She is going to be the fastest Lancer unit in the game with tana (of course She can't acess to flier buffs)and hass good bst (almost villager level)and despite sturdy blow is not the best a skill It helps her Battle physical unit due her High Attack and High defence She would reach 54 Attack 36 Speed and 37 def when She Attack which is Pretty good on a lancer. Outside being the spur ephiram (which is amazing) She dosen't have god like skills like lyn basically is Just un up-graded lance lucina but She is fairly good on her. Being a spur support unit could be actually a Better version compare to hone skills, you can add as many spur ad you want and since It has longer radium is less stressful for positioning. However It required lucina to be near that said unit and unlike hones they dosen't keep if lucina is afar. Of course She cannot use falchion skill like litle regen and anti dragon usefulness but It dosen't matter much. She would prefer having Fury for Better overall bulk and offense however be careful that -6hp May could hurts since she hasn't renewal ability.
2,5) roy. He is actually going to be One of the best Red horse unit in the game, he has his father weapon + heavy Blade in it which due his High Attack even without horse buff is scary,he has a very good Speed which get Better due his a slot, his defences are not high overall balanced but dud horse buffs get Better and his def to due his a slot.roy is basically the best offensive Red horse unit, most or the most popular Red unit are xander and eldigan but all' of them are defensive phased unit while Roy is an offensive One. With his stats and skills he is already at 51 Attack 38 Speed without horse buff and oh boy that spooky. I think Roy is ranked lower due as a very stand alone unit (without buffs) despite being amazing dosen't really Shine compare to at least brave lucina but with buff he would reach another level compare to her. Also keep in mind that without distant counter many would still keep xander (even Thought he has another role compare to Roy but still worse than him ). His bst aren't very fenomal for a horse unit i mean she has the highest among them but still below infantry units.
3)ike there are many misbeliving about him. his weapon has -1 cooldown which is good also It reduce follow ups Attack damage by 80% but i think that means if the unit Attack twice in a row like brave weapon or something he can counter like magic,bow and so on not the very second Attack Itself It ike Attack between the 2 or them. Is a slot is basically heavy Blade without the Attack limit + close def 2. His b slot is Can nullified horse/flier buff that dosen't mean It effective against horse and flier and he can counter ANY buff skills only flier and horse this skills is amazing since It nullied the annoying horse buffs but many would prefer giving him another b-skills like Quick resposte or vantage. Ike is basically Hector without armor, he has High Attack and def he trade some hp for Speed compare to Hector(still slower than his normal self). Brave ike is defensive unit, he has similar def as Summer Tiki at 100% hp when attacked, his Speed since is below average means he would get doubled easily while he has way more Red as is normal self he is vulnerable to unit like tharja and celica (still Red mages aren't very common). His bst is very High is villager/Little manakete level which is amazing. Still i think is actually the lowest ranked between the 4 since Hector does a Better job, he can counter afar,has Quick resposte and eventually even vantage and armor buffs while ike Can deal a lot of damage in his own but he is pretty scary due his cooldown special skills which means he can run eather pretty well. I mean he is not a bad unit the opposite is amazing still while he can easily trade with physical unit sure he can't with mages unless distant counter but using distant counter you would delete his def and heavy Blade skill which he needs only 2 hits to activate eather which is Pretty scary. However is Speed since is low is good since It allow him to have more defensive stats however being almost always doubled especially to this meta Speed oriented is not the thing. While is b-slot is good effect you would easily replace It with Quick resposte for Better defensive option.
This was my Thought i think i would pick lyn as my free unit and of course trying to get the other in the meanwhile. Tell me if you agree or if i made a good rewiew about them