Some relative stats on how platforms are doing with pkgsrc; results found in recent entries to the pkgsrc-bulk mailing list.
NetBSD 3.0_STABLE/i386 96%
NetBSD 3.99.18/i386 94%
NetBSD 2.1/i386 92%
NetBSD 1.6.2/i386 92%
DragonFly/i386 90%
NetBSD 3.0/x86_64 87%
NetBSD 2.1/sparc 82%
Darwin 8.5.0/powerpc 60%
IRIX64 6.5/mipseb 31%
DragonFly appears to be the best place to run pkgsrc, if you aren’t running NetBSD.