Skip the Hercules and the Gemini. If you don’t know if you need 4 channels, you don’t need them.
If you go the Traktor route, the only serious option I’d entertain is the S2 or something with some of the modular NI gear. Currently I wouldn’t feel comfortable advising anything but NI gear with Traktor.
Our current shortlist for non-Traktor starter controllers looks something like this:
Pioneer DDJ-SB2
Pioneer DDJ-RB (RekordBox only)
Numark Mixtrack Pro 3 (or even the 2)
Numark Mixtrack Platinum (bit more expensive than the Pro-series, but still affordable)
Denon MC2000 (while not the most recent release on the market, it is still both technically and in build-quality one of the best around)
Reloop Beatmix 2 (both the original and the mk2)
Don’t be afraid to buy used gear. Starter controllers have often spent their entire lives in bedrooms or other practice rooms. Not much, if any, time on the road. And as you will use it a year or so before knowing what it is you want to upgrade too, it is a serious option.
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