More important than the difference between siding is the difference in construction. The Jayflights use all wood construction with fiberglass insulation while the Eagles use welded aluminum framing in the floors and walls with foam insulation. The Eagle TTs have wood roof trusses with fiberglass insulation while the Eagle fivers have aluminum trusses and foam insulation in the ceiling (why Jayco doesn't do that for the TTs is beyond me). Fiberglass insulation will hold far more water than foam in the event of a water leak, increasing the potential for damage. Fiberglass can settle over time creating "heat holes" but foam is reasonably stable.
The Eagle line has better construction than the Jayflights. There are more 110v outlets available (one can never have too many outlets!). Many of the options in the Jayflight line are standard in the Eagle line and the Eagles have more options available.
Going back to the siding issue. While the Filon siding looks better than aluminum and is far more dent resistant, the aluminum siding can be peeled back for repairs and modifications. Filon is pretty much impossible to peel back plus the foam insulation makes it pretty much impossible to pull wiring etc.
For example, two Jaycos I have considered are the Jayflight G2 33RLDS
and the Eagle 330RLTS
. These have very similar floor plans with the Eagle having a third slide in the bedroom. That additional slide increases storage room immensely but one pays for it with additional tongue weight (the entire trailer is heavier). To accomodate the bedroom slide, the Eagle has less kitchen counter space than the G2. The countertops in the Eagle's kitchen are much better and the range has a larger oven.
Both the G2 and the Eagle have two backwalls available: an entertainment center and an expensive, optional (plastic) ledgestone fireplace. Both walls in the Eagle have a 110v outlet on the sidewalls at the back. The G2 does not.
The two things that pretty much have clinched the Eagle for me were the increased bedroom closet space (which is huge for me since I will be fulltiming) and the welded aluminum framing with foam insulation in the walls and floor. I just wish they had done that in the ceiling like they did with the fivers.