Powerchairs with the drive wheels at the centre are very manoeuvrable, meaning they're most useful in shops, in public transport, etc, and they're a good first chair. Buy the biggest and most robust you can find! Lightweight chairs are pretty hopeless – steer like tanks, no torque, and it feels like you're been driven around in a supermarket trolley.
Above all, I would try something secondhand first. You can never know whether or not something's right for you until you've used it for several weeks, and it's very easy to make costly mistakes. It's not like buying cars, there's very little to go wrong with electric motors; you'd almost always need to budget for new batteries (people often don't understand that if they're not charged regularly, they'll fail), but otherwise you can save 50% or more by buying secondhand.
I've used powerchairs for nearly 20 years, and apart from my current chair (a gift from my late mother, which has 6" wide low pressure tyres so that it'll cope with mud, sand, etc for wildlife watching), they've all been secondhand. Mostly from places like eBay, as secondhand equipment dealers need to make a business profit out of selling them; ordinary individuals are just trying to reclaim house space for something that they or their relative no longer needs!
If you've got the energy, it's worth visiting either a secondhand dealer or an Independent Living-type charities, to try out some models. (I'm not sure whether you have Independent Living in the US – it's a UK organisation that allows people to try out and get advice on disability aids free of charge, without any sales pressure. They helped me choose my first chair.)
Good luck!
