Reply to Kontrol S4 Mk2 + MF3D or DDJ-SX

Hi,

I am looking to upgrade my set-up and have been exploring 2 options, a Traktor Kontrol S4 MK2 with a MidiFighter 3D or a DDJ-SX.
I don't mind about software as I have used Traktor Pro 2 and Serato DJ and liked them both.
I would like to find out peoples general opinions on what would be better as I am in a bit of a predicament.

Thanks,
DJ Foo