Get one with a proper compressor as in my experience anything else is rubbish. We have this one (discontinued it seems unfortunately) and it fills it's 1.5l tank in about 6 hours. Great for drying clothes.
Prem-I-Air 10 Litre Xtreem 10 Dehumidifier with 1.5 Litre Tank Capacity https://www.amazon.co.uk/dp/B005LVGTK8/ref=cm_sw_r_cp_apa_5FnbAbE1XEV6P