I have tried many of the guides out there. I have the Festool TS75 and TS55C as my saws, and use the Festool rails. Here's my thoughts on what I have.
Festool Parallel Guides $300.00
I bought these originally, but ended up returning them. They worked fine, but I do most of my sheet cutting on a piece of foam insulation laying on the ground, and the Festool guilds require being lower than the material. They looked good, and if working off the edge of a table or bench, they'd be fine, but they didn't work for me.
Woodpeckers Parallel Guide system $429.00
I picked this up when it was one of their One Time Tools. It is very accurate and easy to use. I like that it all fits in a systainer, which makes it great for offsite use. It takes just long enough to set up that it is a slight annoyance. If I never left the shop, I would just leave it assembled all the time, but since I do some work offsite, I mostly leave it in the case and use it for offsite work.
Seneca Parallel Guides $249.00
I purchased these soon after they came out. They are my go-to guides. They use the Incra T-track plus, which is great in that you can easily and inexpensively get different sizes to handle larger widths. I don't bother with the paper scales in the tracks, but rather set each width using a story stick. I did not have good luck getting the paper scales in the rails to be consistent, but I didn't spend a lot of time trying. I keep a set of 24" tracks and a set of 48" tracks.
Since I have purchased my guides, TSO has come out with a very nice set. I do not own this, but if I were buying new today, it is probably the one I would get. I really like their Guide Rail Squares and precision triangles. Linked below is the full kit, but they sell it with other rail options for less money.
TSO Parallel Guide System $359.00
I hope this is useful.
Lee