In my opinion, rated speed is completely unimportant.

Most new bows have some draw lenght adjustability built in. Even if it doesn't, if you come close, then you can change it some, by adjusting cable and string lengths.

After you shoot for awhile, you will discover what you prefer. Until then, and it may takes years, just try to avoid any extremes, as in - super short or very low brace heights.

The key is finding a bow shop that knows what they're doing. Great tuning and good shooting advice will do far more for your shooting than any particular bow.