I had Eibach springs on my old car and although it was a totally different car I remember that ride quality was about the same as stock, harsher on hard bumps but as far as regular driving, just as nice. Everyone with H&R springs loves them as well. No my car does not lean. If your's does you can get spring helpers to raise up the one side that is sagging. But that is a bandaid on a bullet wound. Something is wrong because you said ride quality sucks. You said you have some type of aftermarket controll arms so someone has been in there altering things. If I saw your car in person I could find out, but it's hard over the net.
Bad shocks and struts can cause a sagging suspension. New/good shocks/struts tend to extend strongly, a bad strut/shock tends to stay where it is put or worse. Bad shocks/sturts can also sieze up, this happened to my car right after I bought it, it was much lower in the front, the left front esp. Turned out the LF sturt was siezed up. I have been working in a shop for six years and I install suspension parts on a daily. So if one was dead, and the other was good the one side would be higher than others.
Once again hard for me to tell over a wire. Here is what I would do. Try unbolting the shocks from the bottom and see if that helps. Measure the differences or ground clearances of the lower controll arms. If the spring perches are at the same higth, but the top where the spring meets to body is different, you have sagging springs.