the major issue I had with steelies is the weight. your stock wheels weigh around 22 lbs and the black rock steelies I was considering weighed in at like 35lbs or something. So I opted for a set of pro comp alloys, the weigh 27 lbs but are inch wider than stock.
they say steelies are easier to repair on the trail, which they probably are. But if you bend a wheel on the trail, that's a bad day. The other issue is they are more susceptible to rust. plus your wheel choices are limited.
Most people get a 15x8 w/ 4.75 inch backspace. they get 15s because the tires are cheaper. But I stayed with 16s and the price difference tire wise like $20 a tire at the most.
as far as brands go:
2. black rock
3. Mickey Thompson is offering steelies now
4. pro comp