I suppose it is also dependent on what your budget is. I am also on a mac, and have used Kerkythea pretty much exclusively. You can find the X11 install online on the Mac site if I remember correctly. I also didn't have the disk but found X11 online. Thea is now out, and available for a test drive, or if you are running Parallels, etc on your Mac Twighlight sure gets good ratings. Kerkythea is great, but it does have a little bit of a learning curve. However,the way it is set up really gives you a deeper knowledge of haow materials etc work. It also renders biased and unbiased.

I preferred Twightlight render. Very easy to learn and quite affordable.

Thank you so much for your help! You all saved me a big headache