choosing the best

The sensitivity of Paradigm monitor 7 v3 is 90dB (anechoic) and the Kef K160 is 89dB (anechoic), I don’t know where MC get the 94dB sensitivity from???

BTW, 20watt output on a 89dB sensitivity speaker will produce 92.3dB SPL from 10 feet away.

Paradigm monitor 7 v3 Specifications:
3-driver, 2-1/2 way bass reflex, quasi-3rd-order resistive port, floorstanding / tower
Crossover: 3rd-order electro-acoustic at 2.0kHz, 2nd-order electro-acoustic at 400 Hz (lower bass driver)
Frequency Response On-Axis: ±2dB from 47 Hz - 20 kHz
Frequency Response 30° Off-Axis: ±2dB from 47 Hz - 18 kHz
High Frequency Driver: 25-mm (1 in) PTD™ dome
Mid/Bass Frequency Driver: 165-mm (6-1/2 in) ICP™ cone, die-cast chassis
Low Frequency Driver: 165-mm (6-1/2 in)carbon-infused cone, die-cast chassis
Low Frequency Extension: 33 Hz (DIN)
Sensitivity Room / Anechoic: 93 dB / 90 dB
Impedance: Compatible with 8 ohms
Suitable Amplifier Power Range: 15 - 180 watts
Maximum Input Power: 130 watts
Weight: 76 lbs. (34.5 kg)
Dimensions HxWxD: 40" × 7.625" × 15.375" (101.6cm × 19.4cm × 39.1cm)

I think it is not even close, you want the Paradigm. Why? Because you are on a budget, you have to be smart about things. Kef are 89dB sensitivity, Paradigm 94dB. This means you will need almost FOUR TIMES the watts to drive the Kef as the Paradigm. Quality watts cost money. There simply are way more and better sounding 20W amps that would fit in your system than the 80W amps you will need to be comparable with the Kef. 

Of course, if you hear Kef and fall in love, fine. But pay attention to what was used with them. Will you have that? Will they sound as good if you don't? Experience shows it gets harder and harder to find the right amp once speaker sensitivity drops below around 92dB. 

Honestly, it's extremely subjective with lots of variables.  Listen to both in your room with your system, and pick the one you like best...if either.