The Sheerline Trafalgar is an excellent boat, all of the Sheerline boats are well engineered and built to take a hammering. If you check the boat over carefully, and don't cut any corners when building and maintaining the boat, you're almost guaranteed a reliable sail.
In addition from what I've seen and heard, Chris gives superb customer service, and seems happy to help people even if they've purchased a kit secondhand. We get several of these boats at the Dive-in events, and generally they run and run until the battery pack goes flat.
Regarding the Krick Type VII, I've seen two of these at the Dive-in events, one had issues which required modification by the builder, the other sank on it's first outing and had to be retrieved; the resulting flooding killed a battery pack and ESC. I've looked at this boat quite carefully, and I just don't like it. A more experienced builder could iron out the wrinkles in this boat, but a beginner may get into trouble.
The Nikko Seawolf isn't a bad buy for fifty quid and they're very easy to sell on if in good nick- a lot of people buy them just for spares. Also it's small, and thus easy to transport and good for the small pools you find at shows these days.