blue tongue lizards are a lot slower, but are more hardey and proberbly easeyer to handle than a bearded dragon. however having kept both i personally would go a bearded dragon because they are more active (more exciting to watch), and are an awsome lizard. as for monitors, such as the pygmy mulga monitor and the ackie(ridge-tailed monitor) they are a lot cheaper to run (dont need u.v or ceramic heat lamps), all they reqiure is a large tank and a hot basking light. beardy's and blue's need u.v and heaters(can be expensive).
as for tanks melemine is the best. for a bluey, and bearded dragon, a 3ft long, 1ft wide and 1ft high is a minimum. and for a monitor probably 4ft long, 2ft wide, and 2ft high is a good size. u could go smaller for the monitor but bigger is always best.
i like monitors the best but its up to u wich u like best.
small skinks such as the garden skink wich u can find in gardens, woodstacks and stuff often make a great first lizard for younger kids. (i started off with skinks).
hope it helped