The answer is to ask direct questions to the people selling the stoves. So, to the guy selling the Regency, 'I'm also looking at an Englander nc-30. What makes this Regency so much better? What are the weak points on the Englander? ' Do the same with the Englander guy.
Their job is to know their products and how they stack up against the competition. Take a really careful look at each stove and how the controls work, how the welds (if steel) look, take a flashlight and look inside. The more you search, the more you will learn.
BTW, I don't own any of the ones you are looking at and I would not suggest you buy what I have. What I did learn in one full year of shopping was that there are some stores that do not know their stoves very well. I guess many people buy the one that looks the best.
You'll also run into a LOT of people who think any stove that has a cat inside is junk. If you have someone say that, don't argue, just run ... fast. I don't own a cat stove but they are very good many installations.