No desktop printers can print white, except the ALPS printer, which uses ink tapes for four colours and white.
In general terms, a laser printer will give a sharper, and slightly denser result, compared to inkjet, although in both inkjet and laser, density, on clear decal sheet in particular, is nowhere near as good as traditional litho or screen printed decals.
Any design incorporating white, such as a badge, needs to be thought out regarding orientation. If it's possible to print onto white decal sheet, and then trim around the decal, fine, otherwise it's a case of printing onto clear, and painting the surface to be decalled white, so that it 'shows through' in those clear areas which should be white.
Most of the decal paper available for inkjet/laser printers are the same, coming from the same place. I once bough a couple of different packs of 'branded' papers, each of which had exactly the same trade name back stamps, and were exactly the same as those I bought, at about half the price, from a computer papers supplier.
The quality of the image is dependent on the quality of the printer and printer ink used and, although useable decals can be produced, depending on the colou(s) printed, and the colour of the surface the decal is being applied to, density of the image can vary. In some cases it may be worthwhile overlaying two decals of the same design, one on top of the other, to obtain the best results where density is concerned.
Note that laser decal paper can not be used in inkjet printers, and vice versa.