To qualify my remarks....I own upwards of 40 dutch ovens, plus assorted cast iron skillets, muffin pans, chicken fryers, grills, griddles, etc, and have catered, and taught dutch oven cooking classes for over 30 years. I have had the pleasure of feeding a youth group consisting of 125 hungry teens and 12 adult leaders a sit down meal 15 miles from the nearest power outlet on a few occasions. I'm still learning every time I do dutch. I like cooking with other dutch oven cooks, and trading tips and recipes.
First, please understand, dutch oven cooking is a sickness. You didn't just get a dutch oven, you got your FIRST dutch oven.
To answer your question, the standard, or shallow model is the best for biscuits,( and cobblers ) because the radiant top heat can reach the tops of your biscuits before the bottoms ( contact heat ) get too done. I put 2/3 of my coals on the top, 1/3 on the bottom when baking. As soon as the bottoms have just started to brown, I take the dutch off the bottom heat, and put the coals from underneath on top with the other coals.
For food you would cook on top of the stove, like soups, stews and beans, it's almost all bottom heat and the depth does not matter as much. A 12" standard dutch oven is a great way to get started and you will get a lot of use out of it. For casserole type dishes, the heat distribution is about half and half, just like baking in the oven at hone. When you are ready to start doing roasts, and loaves of Basque sheepherders bread, or even doing a prime rib, you will probably move up to a 14" deep dutch. Eventually, you will find yourself stacking the ovens, and making 3 or 4 course meals.
Dutch oven chicken, spuds and onions, and a blueberry cobbler for dessert are staples for river bank meals, or boy scout camp outs. Tender Swiss steaks from beef or elk, smothered in cream gravy, and served with sourdough biscuits make a memorable dinner, served with a chilled lettuce salad and sweet corn that is roasted in the husks on the coals beside a dutch oven.
Don't say I didn't warn you.....take your time, and enjoy the journey. There is a lot of very good eating ahead. If you need directions on some particular dish, or anything else,there are lots of experienced folks willing to answer your question here on the forum, or please feel free to PM me.
Edited by siege - 7/22/16 at 10:23pm