Hey, so I'm an ex masters SC2 player and overall I'd say I'm capable of playing most games at a high level (masters in overwatch, plat in league, etc). This is not to brag, just want to show I'm capable of thinking about game design and balance at a high level. Anyway here are my biggest complaints:
Turrets for all races needs a nerf. 200 requisition shouldn't be capable of stopping harass for the entire early game, especially against ork who dont have a good turret buster till nobs. Solutions for this should either be a significant health reduction or a requisition upgrade. Considering their current state, I'd say 400 requisition would be a good starting point.
Webway gates need a health nerf. Players should be able to punish eldar for mispositioning and giving up map control, however, webway gates are way too tanky to punish in the early game and midgame. These buildings should be fragile, they shouldn't be as tanky as turrets and unit buildings. They should be high risk / high reward buildings if you position them aggressively, atm they are very low risk and very high reward.
Ranger spam needs a significant nerf. This strategy singlehandedly has made the Eldar vs Ork matchup the worst matchup in the game. Ork against a proper player has no chance of winning. For more thoughts on this you can check this reddit post. https://www.reddit.com/r/dawnofwar/comments/676u4k/eldar_rangers_rohahn_is_completely_broken_vs_ork/
Workers need to cost more requisition. It makes no sense that a building unit is 75 requisition. It makes killing them meaningless and it creates this weird strategy dynamic where worker/builder units literally act as a meatshield for your army.... While it is kind of cool in concept, it makes no sense for a strategy game. Workers are workers, they are not soldiers, lets keep them that way. You should be able to punish people for losing workers and killing them should be a detriment to your strategy