I purchased a Z3 for myself and a z3 compact for her indoors. I've booted my z3 up and change the simo to a nano sim and by god it's miles better than my s3. If you use google apps a lot, camera and play about it's great. The reviews i read on the s5 vs z3 from gsm arena said go for the z3.
http://www.phonearena.com/news/Sony-...t-look_id60093
And the s5 mini is a s3 in a different guise but the z3 compact is a compact version of the z3 with slightly less tech spec.
I was lucky and used tesco double discount weekend and the two cost me £707. I'd go with a Sony now i'm converted from Samsung and it reminded me tech loyalty just costs you money and doesn't give you best tech for cost value.