I have been using the UV photoresist method for more than 20 years. In my opinion, the absolute best transparency was made with an inkjet printer (HP970cse, as I recall) on a high-resolution transparency film (it was coated with ceramic microparticles and is made mostly for commercial artists). Unfortunately, in the past several years, I do not make enough transparencies to keep the ink cartridges from drying out. So, I switched to a laser printer and developed a method to improve the density of the image.
Laser Method:
I have used HP LJ4 and HP LJ4101 printers with good results. A Brother HL2270 and probably others (see below) will not work with this method. In brief, I print the transparency on ordinary overhead projection film (polyester), then go over the image with a dry-erase (aka white-board) marker, let it dry, and then rub the image with soft tissue to remove excess marker. One goes over the entire image as the particles are small enough to be retained by the toner. I have attached a full text description and pictures that illustrate the method.
Recent Problems:
As noted, transparencies made with the Brother printer will not work with this method. Its toner is not as hard or stuck as well to the transparency as the HP toner is. I suspect many of the newer printers that use LED's for fusing will have the same problem. The only way to tell is to test it.
Good luck.
John