I love [name_m]Liam[/name_m] but only as a nickname for [name_m]William[/name_m]. On its own plus combined with the m in the middle name sounds a bit short or abrupt.
[name_u]Elliott[/name_u] got my vote. I like how it looks and sounds. Softer sounding names pair well with the middle name, balancing out the x. I like it
[name_u]Elliot[/name_u] [name_m]Mannix[/name_m] is my favorite with [name_m]Liam[/name_m] [name_m]Mannix[/name_m] my second choice. I also love [name_u]Aiden[/name_u] [name_m]Mannix[/name_m] and [name_u]Owen[/name_u] [name_m]Mannix[/name_m]. I like [name_m]Euan[/name_m] [name_m]Mannix[/name_m]. Great list.
[name_m]William[/name_m] and [name_m]Liam[/name_m] don’t flow well because they have back-to-back m’s with [name_m]Mannix[/name_m]. [name_u]Aidan[/name_u] is overused in multiple spellings that it has sadly lost its Irish charm.
[name_f]My[/name_f] favourite three name combo is [name_m]Alexander[/name_m] [name_m]Declan[/name_m] [name_m]Mannix[/name_m] (although I think [name_m]Alexander[/name_m] [name_u]James[/name_u] [name_m]Mannix[/name_m] would be better).
[name_m]Euan[/name_m] is beautiful. [name_u]Love[/name_u] that name, its meaning, its gentle sound in contrast to [name_m]Mannix[/name_m]'s sharpness. I’d advise against Wilco - I think of radio lingo, and people will think you’re crazed fans of the band.
All of those combinations are nice, but my favorite is [name_u]Owen[/name_u] [name_m]Mannix[/name_m]. [name_u]Elliot[/name_u] [name_m]Mannix[/name_m] is good, too. As for three name combos, I like [name_m]Liam[/name_m] [name_m]Alexander[/name_m] [name_m]Mannix[/name_m], or [name_m]Alexander[/name_m] [name_u]James[/name_u] [name_m]Mannix[/name_m]. All of them are good, though.