I have owned both styles to move my tractors and my antique trucks. My low boy (deck between the axles) had a 16,400 lb. gvw with a 24' deck including a 4' dovetail. It was tandem with single 14 ply 17.5" tires. It worked adequately after I changed the brakes out to hydraulic discs.
I upgraded to a 32' hydraulic dovetail that grosses 22,500 pounds that has tandem dual wheels, is a "low pro" model (deck framing dropped down into the frame), and is factory equipped with disc brakes. I am much happier with this trailer because it is so much easier to load/unload, it tracks better without as much chucking, and it brakes better. I was concerned about raising the load up another few inches, but after towing with it I cannot tell the difference, mostly because IMO, it has the dual wheels.
I paid right around $6500 for the low boy brand new and then put another $1500 into the brake upgrade. The trailer was a Kaufman and if you look at their products I would pay close attention to the axles they use to see if the components match the weight rating. The deck over is a PJ that I found lightly used for $10K. ($16.7K new) It is a very well built trailer that uses quality components.
I believe either style would work for you, but I would go with a 30 or 32 foot deck over equipped with tandem duals and disc brakes if I were you. If you can swing the extra bucks I would also recommend the hydraulic dovetail as it makes life a lot easier.