If maximum flexibility is what you're after, Numark's M4 is for you. The three-channel tabletop piece's speciality is its input section. There's a pair of switchable phono/line inputs, assisted by four separate inputs, plus Master and Record outputs and three-band EQ/rotary kills. You're able to check signal strength through a six-segment LED display and it's fully compatible with DJ racks. You'll barely notice the impact on your bank account, either, at the slight cost of £100.
Citronic CDM8:4 USB
Citronic's CDM8:4 USB offers you four channels for £179, each one armed with three-band EQ and individual volume control. Loaded with 12 inputs, its Signature Pro crossfader has a defeat option, there's internal digital delay or FX loop for vocal mics and high/low EQ for each channel. You'll need a fair bit of space to fit it in as it measures a width of 19".