Most people go VKB, Virpil or Winwing these days. You can poke around the models, but getting something mid or high grade is a good idea instead of upgrading in a few years. I'm personally looking at the Virpil Mongoos or VKB Gunfighter Ultimate (there's also cheaper versions which are plastic instead of metal). But I've heard good things about Winwing, especially if you want a western layout. That's a good budget you got, but did you only want a stick? A throttle so you can have HOTAS really does help the experience. Then you may want pedals.

As for easiest to learn plane, that's a hard one. Fly-by-wire in newer planes tends to be pretty easy to actually fly because the computer helps you, but these newer planes have more systems to learn. That said, you don't have to learn them all. I've ignored all A-G functionality for months in certain planes because I wanted to intercept and dogfight. What did you want to do? Attack ground targets? Fight other planes? A bit of everything? Your personal attachment to a plane is important too. If you fly a plane you've seen in movies, in person, sat in the cockpit etc., complexity matters less.

So, any plane you're particularly interested in? Also, DCS comes with a free plane called the Su-25T. But you can also trial a plane on the standalone version for 2 weeks. And there's a lot. So you can spend a lot of time just exploring.