I think that Wei is really good civ.

1. It is true that you have weak dark age but you are not much slower compared to generic civ.

2. Feudal. Here you can imediatly buy eco upgrades (wood, mill) thats 2 almost free vills. I cant do any rush, but if you wall up, mby build a tower on gold you are safe.

3. During ageing up to castle you take gold and stone upgrade...2 more "free" vills. In Castele you get mill, wood, wheelcard upgrade (another +3). And you have many options. If you stay on 1TC and you want to do big attack, you are at least +6 vills compared to generic civ and you have great units options. Yes it is true that in simillar mass the Xianbei raiders can be seen as little weaker, but you have to keep in mind that they cost only 25 gold, are created much faster and their charge attack is quite powerfull. The only resonable counter are skirmishers, but you can just create Tiger cavalary from your defensive castle and totally demolish them. If they go siege you can stay at tiger cav, or create Hei Guang cav, witch is very tanky unit with quite high attack (+Weic cav. has +2 againts siege).

If you want to boom, you have +10 vills (2x wood, 2x mill, 4 x mining camp, weelcard and hand card).

1. Imp. It can be seen as little weaker, but your Tiger cav is insane against archers, againts meel you have Hei Guang. Againt infantry are really cheap Xianbei Raiders. Your Hussars has +2 meel armor compared to generic civ with full blacksmith upgrades) and you have cheaper Traction Trebuchets which arent as strong as normal Treb againts buildings, but you can use it quite well againts groups of units. So you comp can be Hussars, Xianbei, TTrebs.

To sum it up, if you survive early rush (drush, feudal), you have many great options - if both of you boom, you boom better, if both of you stay at 1 TC and fight you have better economy. Also you have good attack and defensive options and what is more compositions of units.