Actually, there is evidence from recent studies that functional languages (Haskell, ML, ...) are easier to pick up by absolute beginners than imperative ones (BASIC, C, Pascal, C#, ...). The notion that a GOSUB is simpler to grasp than a regular function has been long disproven.
Experiments with kids aged 5-10 show that not only they are capable to grasp the concept of function but that they actually are capable of inventing it when they realize they need to repeat a multi step operation.
Basic is universally considered a historical accident by computer scientists and professionals alike and although that is the language I started with when I was around 11-13 I definitely would recommend to stay away from it.
It's fine to use as a prototyping language (Amos/Bltiz) but I do not think it is a good introductory language because it hampers the use of higher level concepts that any programmer needs even very early on.