I'm a hobbiest. I have both of them. I use both of them. I like the ease of using the Seneca guides a bit better. Faster to setup and better balanced, particularly since you can use different lengths of adjustment track on them. I also like their method of working with narrow pieces with an index point that slides under the rail rather than having to add the outriggers as you do with the Festool Guides.
Finally, they store in a smaller space if that is of any consideration for you. I don't need portability outside my shop, but the ability to work with varying lengths of incra track make it easy to throw the heads in a systainer and the track lengths in with a bag with your rails.
If you are doing a lot of sheet goods, the Festool rails are really designed for this. In my experience, if you are ripping solid wood planks, the Seneca guides give you a bit more control, particularly on narrower or shorter pieces where the Seneca guides don't overwhelm the wood.
Both are equally accurate. And both work well. But if I had to choose one set, I think I'd go with the Seneca ones.