Go for the Gardiners SLX 22. Short collapsed length, very light and rigid. Buy the SLX 18 end cap to protect the end and you can take the handle section off to make it even shorter & lighter. The 22 will reach most 3 storey windows, but you can buy extension sections if you require extra length.
I've been using one now for just over a week, really impressed with it.
Regards
Simon