If you are entering an AMHA or AMHR show, as opposed to an open show, the style of halter you use depends on the class(es) you are entered in. For halter, no matter what style of horse you have, you will want to use an arab style halter. For obstacle, showmanship and hunter/jumper, most use a QH style, but some people do use arab style. If you're wanting to get a nice QH halter that's not too big, they do exist, but you have to look around. I have one that is very dainty--the straps are certainly not anywhere near 3/4 inch wide. Good Luck!