I'd pick a simple subject , like a Dehavilland Moth Minor (there are many others) , from Jerry Bates plans , as an example. Why? Fixed gear , one engine , good flyer. And don't think you can't do well with a simple design. Kim Foster has done really well in competition with a beautiful example of a Moth Minor, and Jeremy Fursman has done extremely well with a Tiger Moth. One advantage of Jerry Bates plans is that most (I'm not sure if all do) of his designs come with a three view that Jerry used or drew in designing the plane , which means his stuff is accurate in outline to a three view.

A simple subject is a good first choice for scale, and can be flown regularly, which means you will get to know your airplane well. The general rule in flying scale competition is that if it can go wrong, it will. Easier on the nerves when flying competition not to have to fiddle with stuff between rounds.

However, as Gary SS says, it's always wise to pick something you are passionate about.

Dorin Luck