If you are interested in the Avonds, you might also see if someone has a kit here on RCU they are willing to part with. I see them occasionally. There is also another thread with updates today on building the Avonds. He is making it a bit more scale than you need to, but it is still interesting. I built mine without gear doors, etc, to save weight and keep operations simple.

I have owned and flown the TG F-15 and it is a decent bird. A little smaller and less scale, but still an excellent trainer. I would go with the Dynamax fan rather than the Byron, as you can move it to other DF aircraft down the road more easily. Not much call for Byron fans any more, and they don't perform as well. More static thrust, but less performance in the air.

Between the two aircraft, I think you would like the Avonds better as it is a bit larger and looks very scale. They are both easy to fly, but the Avonds slows down a bit better and takeoffs/landings are more scale in appearance.