You definitely want to avoid the pine. That will be terribly acrid. The oak is a great source and a pretty clean tasting wood. It doesn't impart a huge flavor profile but you know that you have cooked with wood when you do use it. I like the nutty profile from pecan. Hickory has a classic barbecue flavor that most fans of barbecue will appreciate. I find experimenting with different types of woods is a fun experiment. You can order lots of varieties from WalMart or
Amazon. It's a great way to find out what you like. Once you find a combo that works for you then you are in business. Based on my own experience with this model I am certain you will love what you decided on in the end. There are tons of YouTube videos that feature the OKJ Highland but one of the guys that I find most entertaining is that guy Ry. I think his channel is cooking with Ry. If you have a chance give they guy a look. He can be pretty funny.
George