Of your list, I really like:
[name_u]Miles[/name_u] [name_u]Joseph[/name_u] → solid, charming and cool
[name_u]Leo[/name_u] [name_m]Malcolm[/name_m] → bright and sparky, but solid too
[name_u]Theo[/name_u] MacLeod → ooh, I like this pairing - unexpected and cool
[name_u]Maxwell[/name_u] [name_u]Joseph[/name_u] → vintage and lovely - handsome but sweet
[name_u]Jonah[/name_u] [name_u]Forest[/name_u], [name_u]Jonah[/name_u] [name_u]Miles[/name_u] and [name_u]Jonah[/name_u] [name_m]Thomas[/name_m] → love the sweet, warm [name_u]Jonah[/name_u]. [name_u]Jonah[/name_u] [name_u]Forest[/name_u] is cool and earthy; [name_u]Jonah[/name_u] [name_u]Miles[/name_u] has edge and charm; [name_u]Jonah[/name_u] [name_m]Thomas[/name_m] feels classic and balanced
[name_u]Lyle[/name_u] [name_u]Joseph[/name_u] → unexpected and old man vibes
[name_u]Rory[/name_u] [name_u]Joseph[/name_u] → lovely - gentle, rugged and cool!!
I also like [name_u]Callum[/name_u] (but a bit similar to Clara), [name_m]Conrad[/name_m], and [name_m]Mac[/name_m] (but I’d spell it Mack)
If I could mix and match the middles:
[name_m]Conrad[/name_m] [name_u]James[/name_u], [name_m]Conrad[/name_m] [name_m]Thomas[/name_m] or [name_m]Conrad[/name_m] [name_u]Miles[/name_u]
[name_u]Miles[/name_u] [name_u]Jonah[/name_u]
[name_u]Will[/name_u] [name_m]Thomas[/name_m] or [name_u]Will[/name_u] [name_m]Malcolm[/name_m]
[name_u]Mack[/name_u] [name_u]Joseph[/name_u] or [name_u]Mack[/name_u] [name_m]Thomas[/name_m]
[name_u]Rory[/name_u] [name_u]Jonah[/name_u] or [name_u]Rory[/name_u] MacLeod
A few suggestions:
[name_u]George[/name_u] [name_m]Malcolm[/name_m]
[name_u]Jude[/name_u] [name_m]Thomas[/name_m]
[name_u]Toby[/name_u] [name_u]James[/name_u] or [name_u]Toby[/name_u] [name_u]Callum[/name_u]
[name_u]Evan[/name_u] [name_u]Joseph[/name_u]
[name_u]Percy[/name_u] [name_u]Joseph[/name_u]
[name_u]Beckett[/name_u] [name_u]William[/name_u]
[name_u]Leon[/name_u] [name_u]Miles[/name_u]
[name_m]Isaac[/name_m] [name_u]Jonah[/name_u]
[name_m]Rufus[/name_m] [name_u]James[/name_u]