It all depends on your personal painting style, but fo course you don't necessarily know your style yet/anymore.
If you need to mass-produce minis for armies or scenarios instead of painting for the joy of painting, size 1 is a bit small for the largest areas. I use size 2 or even GW basecoat brush (= size 3?) for painting large areas like cloaks. My most used brushes are 0, 1 and 2 and 00 for eyes, and a drybrush for bases.
I use Pro Arte myself, but I would love to try out Series 7. My local art shops don't stock them, so it looks like I'll have to order them from some web shop. I've heard so much praise for them that they must be worth trying. Going for quality will save a lot of grief and actually also money in the long run.
-- Pasi