Realistically, this depends on what you care about.

• For image quality, any of the current Canon SLRs (or even some other things like the EOS M or the G1X) will be better than your 20D.
• To get FPS and AF capabilities which match any of the current Canon SLRs will be at least as good as your 20D.
• If you want dual dial controls and a pentaprism (as opposed to pentamirror) viewfinder, then look at the 60D.
• If you want build quality equivalent to your 20D, look at the 7D.

Realistically, this depends on what you care about.

• For image quality, any of the current Canon SLRs (or even some other things like the EOS M or the G1X) will be better than your 20D.
• To get FPS and AF capabilities which match your 20D, look at the 700D (or the 650D, which may already be discontinued).
• If you want dual dial controls and a pentaprism (as opposed to pentamirror) viewfinder, then look at the 60D.
• If you want build quality equivalent to your 20D, look at the 7D.