My giga rankings are as follows-
2. Fury 325
8. Millennium Force
10. Orion
15- Project 305
I was fortunate to ride Fury 325 on a particularly hot and humid day, which, I am of the belief that makes steel coasters run faster, so Fury 325 was absolutely hauling the day I rode it and blew me away. I feel Fury's first drop is almost identical to Orion's, but everything after those drops is better on the Fury side for me. Orion feels too much like a scaled up hyper to me (and I have a bunch of the hypers I've ridden ranked above Orion because they have more meat to them despite being around the same length), I want a little more layout creativity and low areas that help give you a sense of speed when you're going that fast, which is why I have MF as my 2nd favorite giga of the ones I've ridden. Fury has those low seeping curves between the 2nd hill and the treble clef turn around as it screams above the entry. MF has some nice drawn out parts close to the ground with a lot of trees around as a reference which lets you appreciate its speed (especially at night, MF is the best night ride of the gigas I've ridden). The length of Fury and MF also put them on top for me with both being over 6K ft long.
I will give Orion some credit as it has 2 giant hills in the neighborhood of 200 ft that get you up at a good altitude while also incorporating a good mix of laterals and airtime and the helix is decent.
Project 305 is my least favorite. It feels like a 2 trick pony to me. A decent first drop as trick one, and a high speed course as trick 2. It's the least re-rideable of the 4 I've been on for sure. It does get pretty intense, but there isn't much else to it than that and with so much of the rest of the ride being so small and low to the ground, it felt it was over too quick. The transitions are a bit too quick for my liking as well (not as bad as Mavrick's quick s-curves to me, but still not appealing to me, and yes, I think Maverick is good but overrated).