As regards the choice of full height sheds or below-shoulder height storage cabinets, one thing to consider is footprint. If you don't have a huge back garden, a tall shed with a smaller footprint will hold just as much stuff as a couple of storage lockers that aren't so tall. OK, bikes parked on their wheels are generally no more than 3' 6" high, but they can be stood on end to save floor space, or the space above a parked bike in a shed can be used for shelving, or to hang wheels & tyres from.
Out in a front garden, line of sight and keeping a low visual profile is really going to matter. Front walls tend to be no higher than 3-4 ft, so a storage locker of a similar height is not going to be so obtrusive, and won't block the light out of your front room window like a shed could.