>>195606860He has more tangible progress with her I agree, but at the same time he rarely actually interacts with Makima. He gets extremely excited when he does, and she usually rewards him at those opportunities at well, but at the end of the day he doesn't know much about her and doesn't spend much time with her. I'd describe the relationship with Makima as high-intensity, but sporadic and with big gaps in between, her casualness about these gaps between them (in contrast with Denji's constant longing) is what gives people such a strong impression that Makima doesn't care about him.
By comparison he lives with Power, he works with Power, he generally spends his daily life with Power and at times it shows (teamwork, banter, power's shock when he left her with Makima). There is a slow-build of trust and companionship with them, which on /a/ you'll find people have a particular affinity toward (tomboy/childhood friend/siscon etc). Their relationship is low-intensity but consistent, which I do interpret as being closer to the romantic ideal, however Denji also doesn't notice his own significance to Power (and vice-versa) which is something I've suspected for a while now will end badly for him.
tl;dr Makima vs Power is the "quest for a girl" vs "quest with a girl" respectively, both are romantic plotlines that end successfully, and it could really go either way based on Fuji's intent.