Recommendation on new $400-500 hybrid
I've worked on a number of Marin bikes and they are impressive IMO.  Simple, straightforward design.

Here's the bottom line.  In this price range, regardless of what you get, you are looking at a Chinese-made frame built to "spec" (what the company wants).   Then, various major-manufacturer components are bolted on and the bike is shipped.

They are all really rather similar; variations in frame geometry are minimal, variations in component spec are also minimal.  It's common to throw on an "upgraded" rear derailleur as this catches the consumer's eye... Costs the manufacturer only a few bucks more.

Not that these are not perfectly fine bikes... The main thing you are looking for is fit, which you already recognize as important, and the best components you can get for your money.
Most hybrids are made with a frame that leans more to the "road" type, with a straighter top tube.  Most mountain bikes have a more compact design with a sloping top tube so that the rider can maneuver on the bike while off-road.
The old "standover height" or "inseam" height measurements date to when road bikes were built with the standard diamond frame with a flat top tube.
Modern bike design is a little more flexible.