Ike or Ryoma?

That Ryoma has perfect IVs. Ike needs his bulk to shine.
I'd invest on that Ryoma* for sure, unless you really like Ike.

Both,Ryoma is especially good since you got the best IV for him.
Ike is decent,+att is its best boon,-def kinda suck but welp,it still usable.

I have a +atk, -def Ike and his bulk isn’t so big a problem. Train both and try them. It depends what you think your team needs, as although Ryoma has great Boon/bane, he plays differently to Ike. Ryoma is pure offence, whilst Ike is defensive

both will do just fine, invest in the one you like more. If you have no preference, then go by the play style. Ike will be seeking Aethers out quickly with heavy blade, which can useful against almost any foe. Ryoma's benefit is obviously the speed so if you find that more useful then invest in him first. Keep in mind though that IS seems to be giving more answers to deal with the one round KO meta so Ike could start to outshine him more and more.

Ryoma, all the way, man. You got very lucky IVs.

I use a +atk - def Ike myself and I like it very much.

Ryoma and Ike fill similar, but slightly different niches. Ike is the guy that you want to kill people with in one hit, because his speed is not very serviceable. + Atk is great in this regard. You can run vantage here to have him bait mages, as he will kill most mages before they can attack. Not having - res means he may survive some blue ranged initiations too.

Ryoma is the guy I use when I need someone to duel as well as get a kill on the counter. Because his speed is so high, he most likely won't be getting doubled. Because of this, he is pretty safe, but he won't be one-shotting like Ike does without the +atk. Also, he is still worse at soaking physical than a -def Ike, something to consider.