Free Brave

You don't need to choose yet, the free roll option isn't going away until next year. Wait until you know what you need, then take it.
Or pick veronica.

Choose Veronica, She Have Cookies...
Or Hector, For The Incredible Stats,But If You Think That You Need A Nerfer And Buffer Choose Veronica.
She Start With A Perfect Base Kit And,If You Don't Like It, You Can Fodder All Her Abilities For Someone,Because Most Of Them Are Locked To 5*.

Ephraim Would Be A Good Idea For Hitting Very Hard, Having A Base Atk Of 38 With Neutral Ivs, So You'll Have A Better Grima.
His Defense Is Very Good To, Allowing You To Give Him Bonfire( For Immediatly Things) Or Ignis (For Much Damage But More Charging Time).The Only Bad Thing Is Speed, But With Special Fighter He Won't Have Problem.

Hector Is The All Around Of The Four, Having An Incredible Defense Of 39, An Unusal Resistance Of 28, A Fantastic Atk Of 37.The Only Bad Thing Is The Spd, But With Quick Reposte And Bold Fighter He Won't Have Problems

Celica Is The Nuke: Fast And Strong, But Fragile To Mages And Lances, Maybe Even Swords. Her Speed Is Very Suitable To Beat Enemies Who Are Top Tiers(Hectors,Hardins,Maybe Effie To) And Her Defense Isn't Bad. L&D Or DR4 Are The Best,Knowing That With Base Ivs And L&D She Will Have Atk Of 54 And A Spd Of 47.

This Were A Quick Analysis Of The Brave Heroes Of This Year.Maybe It Was Useful, Maybe It Was Useless.The Choice Is Yours And Lemme Know Who You've Picked.
Boobye!

Do not choose Veronica when you have her with good ivs, the merge is pointless since you can't really score high with her bst anyway

Hector is probably the strongest out of them
Ephraim is really strong too and the only source of special fighter so if you end up not using him he's good fodder
Celica is good but kind of boring, db4 is interesting fodder if you have someone who wants it but otherwise not worth picking
All depends on who you already have, the skills you want , which character you like most etc

Hector. He is by far the strongest one on the banner. He fits perfectly with Armor Emblem and Mixed teams. He also requires very little investment to use well

Out of the options for the free units, Hector has the best neutral stat set. And his base kit is flawless. Add Aether and he can sustain himself during long campaigns like Tempest Trials, not to mention adding 6 res to himself and anyone next to him every even numbered turn.

Brave Ephraim will be the easiest to summon because the green pool of 5*s is the smallest. And Ephraim benefits from dumping his spd stat if you can get him with a spd bane.

B! Celica will be the hardest to pull due to the over crowded 5* red pool, and she is essentially a power creep of F! Celica and functions very similarly and she does not come with distant counter. So, you may be hard pressed to choose her over your current favorite red sword unit. Also, her art is ugly. Urine yellow, really IS? XP

So it comes down to Hector or Celica. If Celica is your fave character then go for her. Otherwise, Hector is a great blue unit to back up your fave sword unit with an excellent base kit that provides both solo power and team support.