Voting Ikki
Skill- while garou has mastered many martial arts by crushing dojos, i doubt he knows more than 128. And while both could copy eachother techniques, most of the ones Ikki will be using (except trackless step,and by a large stretch he might be able to copy the body control) are arguably only truly useful if you have a sword or some kind of edged weapon,same thing for garou's and being barefisted(except abandonment,but Ikki already has a better version of that), if they started learning eachother techniques, Garou would ran out before Ikki, leading to being overwhelmed. Ikki's precog is also better.
Also, garou doesn't have much experience with sword users, the only ones he fought are spring moustache(rapier, wich he countered by letting his hand get stabbed) Royal ripper(who beat him in this key) and Stinger (who wields a spear)
AP- Garou wins by a stomp except for Rasetsu(who i don't remember the value, but am pretty sure the AP is higher, plus some techniques can ignore durability to an extent) p.s(garou might be able to ignore some of thee effects,due to Type-2 immortality)
Durability- See above, only Rasetsu has a chance of dealing damage
Speed- equal at the start,but Ikki blitzes with Rasetsu(Garou's precog allows him to fight opponents who can blitz his senses and body to an extent, but i really doubt he will be able to even perceive a 100x speed difference)
Stamina-Garou wins here, dude's such a monster it gave him type-2 immortality (also, if he survives Rasetsu, the backlash is going to put Ikki in a corner)
Verdict, as long as ikki doesn't job a lot(extremely Ooc btw), goes for Rasetsu as soon as possible and aims for the head,or limb removal or cuts Garou in half, he wins 10/10. If he only cuts deep and tries to incap while avoiding permanently crippling or killing, Garou gets back up and adapts and likely beats the backlashed Ikki to death.