The top loading brushes are easier to use for reasons already stated.
And once again (at the risk of sounding redundant) the level to which you 've
built your skills will determine which make and model to choose.
Personally I've found that i can get the same detail out of the coarser tipped brushes as i can from the ones that are built like swiss watches.
The key thing is to enjoy this "addiction" and have fun.
