Ok, I have finally built both Glen's Garage's kit, and DIYAutoTune's.
First impressions: Glen's Garage's packaging is much nicer, he uses antistatic bags for sensitive parts, little ziplocks for normal parts, and the ICs come on foam in plastic boxes. DIYAutoTune's kit comes in plastic antistatic baggies and ziplock bags, all ICs come on ONE foam block.
BOTH kits come fully labeled and components are in groups (capacitators, resistors, diodes).
Fit and finish goes to Glen's Garage. If I had my camera, I would take pics. The DIYAutoTune's kits have the connectors cut-outs for the serial and db-37 as just rectangles. The Glen's Garage ones have CNC'd endplates, and the db-37 is firmly held in place by the endplate (like on the back of a computer).
I also had to file down the sides of the DIYAutoTune kit for the PCB to fit in the case, but thats is known to happen because of slight differences in the manufacture of the boards.
Assembly was fairly simple for both, but the DIYAutoTune's kit was missing 2 diodes (good thing I had spares from when I blew one on my install)! It also came with other diodes that are usually not necessary or not recommended for most builds, but are good to have if you have an "oddball" efi system. The Glen's Garage kit only comes with the most used and recommended parts.
Now delivery time, Glen's Garage usually has around a 3 week or so wait to recieve your kit because he does get back ordered, especially in the holiday season, while most DIYAutoTune kits are in stock and ready to ship.
Conclusion: If its your first build, and don't mind the wait, get one of Glen's Garage's kits. If you don't like to wait and don't mind the slightly less perfected finish of the kit, get the DIYAutoTune one.
Just for your information
Mario