There's really no point to limiting yourself to only one or two types of magic, if you're putting the attribute points in intelligent you may as well put at least one ability point in each school so you can cherry pick all the best.
Keep in mind that it takes 15 points to max a school, and you get 49 total, so if you intend to actually cast max level spells from each school with no AP-penalty you can max 3 schools at most. A lot of (important) spells are also very situational, and having 3 spell slots can leave you unable to cope with unforeseen situations.
This also leaves you with rank 1 in 4 other abilities, or one rank 1 ability and one rank 2 ability.
