Hi Ari,
The first suggestion I would make would be to talk with Dreamfoam on the phone about the Aria. They will know more than anyone about which of their options will most likely be the best “match” for different BMIs and sleeping styles based on “averages” and the more information you can provide them the better you will help them to help you make the best possible choice.
The Dreamfoam Aria uses a 6" 1.8 lb polyfoam core, above which is 1" of 4 lb memory foam, above which is 3" of 4 lb gel memory foam. Dreamfoam makes mattresses that use high quality materials for their budget range and have great value, but I would also be aware with a higher BMI that it may also be worth considering higher density materials unless budget is the most important criteria because this would also increase the cost of a mattress. There are some good foam density guidelines in post #4 here where I expound a bit upon this. Post #3 here also has more information and suggestions about heavier weights.
Phoenix