Street or Track is the one I would go with. I know you want to save money...but SoT's coilover systems(front and rear) always have positive reviews about improving ride quality over the stock components, even though they are performance orientated. They have "street" kits in addition to "sport" kits. In the end, if you are looking for improved ride...its not the spring that is going to give it to you, its the SHOCK, in particular, matching the correct shock to the correct spring will result in the best performance ...or alternatively the best ride. I would not touch a cheap coil over kit with a 10 foot pole, all that cheap mean is that no real time and effort went into matching springs and shocks, and do research and development time went into testing. Sure...it might bolt up and allow you to raise or lower your car with a coilover wrench....but whats the point of that if it doesn't improve lap times, slalom times, or skidpad times? Ride height adjustments can be made using lowering blocks or cutting coil springs...if you arent getting actual performance out of a coil over setup you are wasting your money.
Take that 4 link you listed above. Not knowing exactly what kit it is, I can't say anything about it one way or the other, but looking at it, I see links without heim joints, relying on bushings....which is fine, but it means that there is deflection that would not exist in a higher quality kit. I see a bunch of weld-on brackets, which are also fine, but its a big risk to take if you find out you are unhappy with the final product, every time you weld a bracket onto a rear axle, you are taking the chance of warping the tubes(well in reality you ARE warping the tubes) there is a good chance of ruining a housing if you change the setup multiple times because you weren't happy with the first setup you chose. I also see what look to be cheap shocks that are bound to give a less-than-ideal ride. Shocks are the one part of the
suspension you really don't want to go cheap with.
What I am getting at here is that a cheap kit will cost you more in the end than buying a more expensive kit that you KNOW many people are happy with because you will be changing things out multiple times until you are happy with it. What happens if you buy that kit you listed and it rides like most cheap coilover kits ride...harsh and uncomfortable because of poor shock and spring choices? What happens if it has a tendency to bind in corners because not enough actual driving and testing has been done with it?