Ryanair coach is the most convenient, since it leaves from outside the airport and drops you off at the rue de France entrance to the Gare du Midi.
The train also takes you to the Gare du Midi, but you have to catch a shuttle bus to Charleroi south station.
However, the train is much more civilised.
Costs are both €10 single fare.
The Ibis hotels (3 in the city) are 3 star and you can access details of these via
www.ibis.fr. Also, the Ryanair website hotle booking service has some cheaper options.
Brussels is a small town, so so long as you are reasonabyly near a metro or tram stop, location isn't as important as in larger cities.