XBox is usually quite presentable. Wasn’t really a fan of the launch 360 but the redesigns were good. Series X and S and the One X are top contenders.
Sony is hit and miss. PS3 was nice in its time as was PS1. The PS3 Super Slim however was not. PS4 was okayish but the PS5 is hideous. What were they thinking really. This thing is so appalling it actively makes me not want one. Definitely the worst looking main console out there.
Nintendo usually flat in this regard. None are ugly, none are exceptional. Still though most gravitate to a positive side. Except the SNES, the PAL SNES/Super Famicom I mean. Though it’s still not ugly it would maybe be a weird look for something that came out today, but relative to its time this was a looker.
Of the other ones, Atari 2600 was quite nice, as was SEGA Dreamcast of course, this latter one is one of the main contenders actually.
Picking a winner isn’t really easy, for me it’s down to Series X, SNES (PAL) or Dreamcast. Maybe I’d actually say Dreamcast.