As I mention above, I think that the Aulos 509B’s 6 and 7th holes are somewhat easier to reach than the The Yamaha Ecodear, and also somewhat easier than the 304B. But since you say you are only just starting to learn the alto, it would be a shame to run out and buy another one just for a slightly better right-hand stretch, I think.
I think that the keys on the alto Mollenhauer would make it easier for you. Only slight wrinkle might be that keys are somewhat harder to press down than just covering a hole (of course). So you are gaining an easier reach at the expense of a harder press.
When you say “Breseden resin,” do you mean the Bernolin resin? If so, the 6 and 7 holes are easier to reach (with the 442 model) than with the other recorders discussed here. You also would almost certainly get a better recorder than the Mollenhauer Canta (kind of a low-end model). I’m not sure about the Moeck, but if is in the same price-range as the Mollenhaeur, then it is almost certainly not as good an instrument as the Bernolin.
So if I were you, I’d try to get by with the plastic Yamaha; maybe get the Aulos 509B. If nothing is any good, you could spring for a Bernolin. It really is noticeably easier to reach the 6 and 7 holes.