Here are the comparative stats, and you can see that the Sukhoi variants are much better than even the souped up F-18E superHornet! Tell me another aircraft that can fly further than an F-18 with external tanks, when that plane has no external fuel tanks itself. Let me see: The A-6 (killed off), the F-14 (the plane is being retired, and the tooling to make it was destroyed) and the Sukhoi.
And the Sukhoi has the added advantage of only costing 8 mil a piece, and being able to outmanouvre, outshoot, outfly, and carry more weapons than the F-18. And the Su can also detect the F-18 at a longer BVR, meaning it can shoot a R-77 AMRAAM-ski and turn before the F-18 detects it and shoots off an AMRAAM.
If third world nations have better airplanes than us, then that means Russia has better airplanes than those nations', and that means we have indeed a big problem. I do not think that buying Su30s is the solution, however. This is like a patch on air superiority defficiency.