So when it comes to the design, I definitely prefer the design of the Preon. In my opinion, it looks a lot classier and cleaner. It may not be as easy to grip as the E05, since it lacks knurling, but I've never had any problems with it slipping out of my hand.
Quality wise, the Preon again wins. The threads are much smoother on the Preon. That may not mean much to some. There's definitely a noticeable difference in the twisty action between these two lights. If they were clickys, it wouldn't matter at all.
As far as the actual light outputs go, they're pretty similar. The E05 has slightly more lumens with 85 as its max, while the Preon puts out 84. That's an extremely minimal difference, so you just have to decide what light fits your preferences better. The Preon does boast more modes, but honestly the various strobe and other special modes are pretty worthless in my opinion. There's a decent difference in max runtime that's worth mentioning. The Preon can run for 23 hours on low, while the E05 can only go for close to 15 hours. The Preon's low mode is dimmer, coming in at 2 lumens opposed to the E05's 8 lumens, so that explains why you get more runtime. The last thing I think is worth mentioning is the tint of the beam. I personally preferred the tint of the Preon. It just looked a lot nicer in my opinion. No matter which light you choose, you outputs will be extremely similar.
Neither light is going break the bank. You can pick up both lights for $20 at this moment in time. FourSevens put these older Preons on clearance on their website, since they recently released an updated version. This Preon is still perfectly fine, and honestly I really do recommend it. I think it's a steal for $20. The E05 is just average, and I don't think it's worth the $20.
So there's my pretty basic comparison between the two lights. Like I said, the Preon P1 is the clear winner. I think it just comes down to what your personal preference is. I've got a more in-depth review on the E05 out already and will be getting one out on the Preon sometime soon. I hope this helped you if you were looking for a good AAA light. Either one will serve you extremely well for the price. Thanks for looking!