i generally always and would recommend sending parcels by signed for carrier, express or 48 delivery or 3-5 day what ever, but the signed for bit is the most important. it also serves that you will have proof of posting . Always put in the comments box when sending with carrier, that you want a clear signiture and printed name to accept delivery, and do not leave at the door or so called safe place or with neighbours.
i would also send small letters and packets this way too. i do not or would not recommend sending standard parcels or signiture not required.
i would also pay carrier by credit card as this also will be another way of prooving postage, as you will have a recept.
i believe that if you use the internet for speed then you should get your parcel just as quick as what you ordered it..
Postage may be a little more expesive but when you want something then you want something quick and of course some proof that it was posted in the first place.