Hi guys

I would like to have your expert advice regarding air condition, What do you think of the following system and are they suitable for medium size bedroom (3.6m x 3.55m)

Mitsubishi Heavy Industrial SRK25ZG-S (2.5 Kw / 9000 Btu) Inverter
Mitsubishi Heavy Industrial SRK20ZGX-S (2.5 kW / 9000 Btu) HYPER-INVERTER

Or

Mitsubishi Heavy Industrial - SRK35ZG-S (3.5 KW 12000 Btu) Inverter
Mitsubishi Heavy Industries SRK35ZGX-S (3.5 kW / 13000 Btu) HYPER-INVERTER

I’m bit confuse for how much KW do i really need? 2.5 or 3.5? i just want something best cooling & heating! And which above model is the best?

btw im from uk!

Regards
FiReDuCk