Yes, definitely test ride as many as possible, if you can. And not just once around the parking lot; that won't tell you very much. As someone noted, bikes with fairly upright seats and low bottom brackets (generally long wheelbase or compact long wheelbase bikes) are typically easiest to learn. You could probably hop on something like a Sun EZ-1 and just go without any real learning curve. But unless you run a fairing, these bikes are also typically less aerodynamic and therefore slower than short wheelbase bikes with more reclined seats. Trikes are a whole different category. There, the principal difference is between tadpole (two wheels in front, one in back) and delta (one wheel in front and two in back). Tadpoles are much more common, but deltas have their advocates. If you're like most 'bent riders, your first recumbent won't be your last. So, test as many as you can, but don't be afraid to jump in. Like others, I would encourage you to buy used. Trikes are in pretty high demand, so bargain trikes are not easy to find. On the other hand, the market for two-wheelers is soft, so if you look around you should be able to pick up something nice for relatively little cash. In addition to Craigslist, Facebook Marketplace can be a good place to look.