3d max
I've worked with earlier versions of 3ds max, and its default renderer was pretty quick. I think most 3ds renders I see today are using the vray renderer, which I haven't used but may up the road for cinema4d. Some renders are very slow, such as bryce, even poser depending on the settings, vue (some nice results). Carrara is pretty fast but depending on settings it can slow down quite a bit. With carrara I have had a few renders initially mistaken as a photo, and certainly, that level of realism is the holy grail for me.
Right now 3ds or May are out of budget (3k to 6k), but who knows what other program I may be able to try.
Thanks for taking time to comment!