Cake Decorating: icing/frosting spatulas

Hi,

I'm a beginner in the cake decorating hobby so I wanted to ask for advice from everyone on which kind of spatulas to get. It really bums me out when I've made the perfect tasting cake, yet I don't have the tools to make the icing go on perfectly. I'm using rubber spatulas and knifes, since I've been keeping it on budget. But now I want to invest for the future!
I have a master set of Wilton tips but go figure - no spatulas.

So how do I choose? I see straight and offset and of course the various sizes, but which are the best and easy to maneuver? Does straight and offset make a difference? I really want to make my icing smooooth... especially for whipped cream based icing

Most cakes I bake are 9inches and in the future I plan to make 3 tiered cake as a project as well as petite fours.

Any icing tips would be greatly appreciated as well!

Love you guys!