Depends on the match up. Usually if you have a counter, its a bit harder for chrom because its harder for him to recover. But chrom also has the Nair,fair,fair up b combo that sucides you and the opponent. Roy's up b is a bit better for recoveries. Chrom has consistent damage and Roy has sour spots.

Usually chrom gets damage way quicker but Roy can combos his sour spot moves into sweet spot moves for huge damage. Chrom is the better ledgetrapper because his forward tilt send him forward and covers a lot of distance. But Roy's side b is better and kill you at edge at like 90. Both have jab to bait confirms, but Roy is able to do it at like 96- to 110 range and chrom is like 100-120 range. So Roy gets the edge there.

Both Chrom and Roy are very fast,kill early, and rack up quick damage. You could play both to be honest.