i love hot dogs from street vendors. i make it a point to try street meat wherever i go in north america (i didn't see too many hot dog stands in europe,
personally, i think the hot dogs from toronto are by far the best. obviously my bias comes from having grown up near toronto, but i'll give my reasons for my preference below with comparisons to some of the hot dogs i've tried in american cities
the selection of condiments at a toronto hot dog stand is amazing. being such a multicultural city, it is common to find stands that have vietnamese hot sauce (sriracha) next to jamaican hot sauce and german mustard. basically all the hot dog stands in toronto serve the same hot dog, grilled and on a yellowish bun. the only thing that differentiates each stand is price and condiment selection, condiment selection being the most key factor in choosing a hot dog. if you want mayonnaise, you'll have to nudge and wink at the vendor to get it from under the cart, as having mayonnaise out apparently violates some health code. if you're lucky, they may also have cheese sauce in their cache of condiment contraband.
generally your basic hot dogs will cost $2.50 - $3.00 on a typical street corner, and if you're near a touristy area or in a sports stadium, be prepared to be robbed of double that amount. street vendors will also have vegetarian, italian and polish sausages for a bit more.
been to new york and i'm not a fan of steamed/boiled sausages. meat is smaller than toronto, and sometimes the water from the sausage makes the bun a little soggy.
chicaco style of hot dog is apparently made unique with a standard selection of condiments. i believe it is relish, onion, mustard and celery salt. no ketchup. not bad, but again, i'm not a fan of the steamed weiners and they're quite small.