On paper and specs alone , the Z3 is probably the best of the bunch. It's a true pocket powerhouse. But in everyday use, the S5 Mini will be fine. I've an S4 Mini and its more than sufficient for my purposes. An 8mp camera is fine for Facebook / Instagram pics.
The fingerprint scanner / heart rate monitor may be redundant (but useful to others), but still nice to have features. The HTC is too large for a Mini (surplus bezels), but friend of mine has it and loves it.
The Sony is the best of that lot, but more expensive no doubt. Best thing is to go to a store and have a play with each; there are positives / negatives to all these devices.