I personally prefer a thoroughbred. They have a bad reputation but honestly I ride them on and off and very rarely find something they aren't willing to do. English and western and they do well. They can require a bit more of a gritty rider but overall good minded and well hearted.
I think that there is no "best". If a horse is suited for the discipline, while remaining sound and is happy with its job, that's all that matters. There are some breeds (QHs, TBs) that are suited for more than one discipline and are able to do well in most.