[adr_]

I wouldn't call it more verbose.

AT&T:

    sub    $0x8,%rbx
    callq  *%rax
    mov    (%rbx),%rax

Intel:

    sub    rbx, 0x8
    call   rax
    mov    rax, [rbx]

Intel can be written with:

    mov    rax, QWORD PTR [rbx]

But it's redundant and assemblers don't expect it. It's only necessary in a handful of places to avoid ambiguity, as opposed to the incessant size suffixes and $/% prefixes, which make AT&T feel more verbose to me. Definitely a matter of familiarity, though.