I've kept a few different salamanders. My current favorites are alpine and marbled newts. Alpines are really simple and low maintenance, as long as they are kept in a cool location, with lots of aquatic vegetation. I keep them fully aquatic.
Marbled newts are bigger and more colorful. I keep the adults terrestrially in the summer, and aquatic during the breeding season. I suppose that adds a small amount of complexity, and requires more space for the extra aquariums, but to me, that makes it interesting. I really haven't had much in the way of negative experiences with these two species.
I also like native salamanders. I've kept tigers, which are big and hungry. Easy to keep. I've kept blue spotteds, which I like very much, but they are secretive and seldom seen. Red backed salamanders are another native that I've kept. They actively climb and hunt at night, which is fun to watch. They are also incredible escape artists, and require smaller prey. Mudpuppies require large enclosures and clean, cool water, but it's really fun to watch them hunt and eat. They have big appetites, too.
There are quite a few other species that I think would be neat to have, but like everyone else, I only have so much time and space for them.