Combining GH with test is ideal. GH will help you produce new muscle cells and test will help to grow and mature these cells. Usually, this question is asked the other way around. Steroids are superior to GH for gains in bodybuilding. Test is the base steroid to use in your cycles. With test, you can make amazing gains, for a number of cycles. Then, as those gains slow, guys add other steroids to their cycles and spark new growth. Down the road, adding GH to the plan will help to push just that much further, as well as help with leanness and quality of muscle.
If I given the option to take one supp, on top of proper diet, my answer would be test. For bulking up or cutting down, test is king