I've been using Supermachine for well over a year now, and I have to say, I'm really impressed with its performance and the quality of the genereated images. It’s become my go-to tool for photos, more so than other platforms like Artsmart or Logo Diffusion, which I own, too.
One of the standout features of Supermachine is their quick integration of new image generation models. For instance, the FLUX model was available shortly after release, and they now offer multiple variants of it. That's a contrast to Artsmart, which hasn’t shown much progress; they even charge extra for generating multiple variants simultaneously, which I found quite disappointing. Supermachine offers this feature even in their lowest Tier (at least when I bought the deal).
I initially purchased Tier 1 with Supermachine, and I'm seriously considering upgrading. The FLUX-model has been particularly impressive, producing excellent results.
Be aware that the deal is not refundable, though, but giving it a try with Tier 1 is in my opinion a no-brainer if your are looking for a great tool for image genration, espacially when it comes to realistic looking photography.
EDIT/Update: My assessment of the quality of the generated images primarily relates to the FLUX model available in SUPERMACHINE. Many of the other models do indeed not always deliver such good results. However, as long as the FLUX model is available, I consider SUPERMACHINE to be recommendable.