That's partly true, if both are on the same level once you meet them, and their stats don't differ too much, then your first NPC is at a higher level and better. The best thing to do is try out all the NPC's in your games. When you know their strengts, you keep in mind who you want in your party and get them as soon as possible in the next game.
When I picked up Sarevok at the start of ToB I found him upper crap, being at a much lower level then my two other tanks, so I kicked him out again.

I don't use too much magic either, actually only in the big fights, too much fuss most of the time.

Another basic rule: Try not to mix up contradicting alignements too much. Like minsc & edwin don`t get along too good .

Just try to get some decent melee fighters (don`t know what you play yourself so that might influence who and what you need), someone for healing, some with thiefskills, and preferably 2 persons with mage-skills. Although you don`t fancy mages a lot, you defenitely need them, once they get on higher lvl you can`t imagine how you would survive without them. So i`d advice at least one mage or sorcerer and someone that could backup (thief/mage, bard or cleric/mage for example) can come in handy.

Every NPC has it`s strong points, and most of them have their own quests as well. They all interact different. So it`s really worth just trying to form a balanced party and see how it works out. And then play the game again. And again. And again.

whoops, bit more drunk than i thought i was...