This fight really makes me realize how bare Chrom's page looks compared to Alm's...We don't even mention Falchion's healing abilities on Chrom's page.
Well, they both fought big bads of pretty comparable sizes and threats who compare pretty well, they both had huge adventures and are reigning leaders for their armies, and they both even the same (well copies of the same) sword. So Strength, Skill, and even Gear don't tip the scales too much here.
Alm has a ranged attack, which is a major point in his favor, and the ability to get small bursts of time to go back briefly and try again is super useful.
But Mila's Turn Wheel doesn't last forever, even if Alm does spam it, and damage and advantage on Chrom is lost since everything turns back with it. It's more a 'do over' than your typical time-hax advantage. And Falchion's natural power to heal, along with the two being pretty on par, means the ranged attacks probably won't put Chrom down before the distance is closed for CQC, and the damage is somewhat lessened when Chrom gets there.
And Chrom's gimmick attack negates defenses and heals himself even more in one 'motion'...The second Chrom closes the gap he gets a ridiculously good amount of advantage. He's hitting harder than Alm is suddenly, Alm can't tank or block the attack as well, and the attack heals off the damage done to Chrom.
Turning back with this knowledge would be useful, but Chrom only has one goal and that's to pin Alm down. Making time for the motions of that range attack means Alm's going to lose ground doing it, and Falchion's natural healing is going to help mitigate the damage as Chrom plays catchup. Once Chrom's in close, Alm's options stop having major advantages and he can't defend against Aether's pair of really decent effects. It's not an easy fight, but Chrom has everything he needs to tank until he can overwhelm up close. I vote for the one who somehow got into Smash.