SEnukeX is great, obviously.
However, I feel like making a comparison between it and SErobot at this point in time is ridiculous.
SErobot is currently in a very early pre-launch stage. This is exactly why you can get it so cheap (they have stated that it will be subscription-based at launch). It's kind of like making a pre-production purchase: You purchase the product before it's ready to help them fund the completion of it, and in return you get a very good price.
In my view, SEnukeX is incredibly hard to compete with, and so I imagine that SErobot will be designed to be a near-match in performance, but will be a lower cost alternative. This will make it very attractive to all the newbs who aren't yet making money with SEO, and find it hard to justify (or even afford) the $127 per month price tag.
Here's my personal recommendation:
1) If you are new to SEO and short on cash, get SErobot (in this case I would actually recommend that you stick to programs you can find for free until you make progress, but that's not really answering the question you asked).
2) If you're making money and you can afford SEnukeX, get both. Get nuke because it's awesome, and robot because it's a one-time payment of $250 right now, and that's nothing when you figure it's an investment in your business. Plus you could always sell of the license later or set it up on a VPS or something if you decide not to use it all the time.