Re: J-xx
The J-10 is a good domestic aviation program to produce multi-role capable light combat aircraft similiar to the F-16, MiG-29, or Mirage-2000. It's a good replacement for the J-6 & J-7 fleet.
The JH-7 is serving with PLAAF's naval aviation and probably serves similiar capability as Dassault Super Etendard or Mirage F-1 configured for naval strike missions, with 2-4 air-launched anti-ship missiles.
The Su-30 is prolly a better strike aircraft, but the problem here is that the Russians might not want to assist the PRC in integrating domestically made missiles (C-802/C-803) with Sukhoi aircraft. Instead, they'd prefer to sell China their own missiles.
So if you want a platform for launching C-802/C-803 missiles, you might be stuck with your own aircraft. It's not the best but not bad either. Imagine a future scenario where you send a pair of JH-7A's, each armed with 4x LACM's, against a surface target. The JH-7A's can launch their munitions from as far as 400 km away and escape, and you only need 12.5% hit rate (from 8 missiles) to mission-kill most targets.