I recently installed some BC Racing BR-type Coilovers on my F30 328i msport and am really enjoying it so far. My reasons for getting coilovers are very similar to yours: 1) lower the car for better stance 2) 30-click damper adjustability for compression/rebound ride to make ride as close to OEM as possible, while allowing me to stiffen the ride enough to compensate for a lowered car (bumps, scrapes, etc...)
Coilovers over Lowering Springs was an easy decision for me. The springs are certainly a less expensive option, but i read enough about the harsher rides people encountered that i knew getting new shocks with damper adjustability was a must do. If you factor that in along with installation costs, its pretty much a wash. I paid $1380 for my BCs which includes installation. I hear that springs + dampers + installation is going to be around the same ballpark, but i can't confirm that for sure.
The other benefit of coilovers is that all the pieces are matched and tuned to work together optimally. BC goes as far as dyno-testing each damper for their compression/rebound rates then matching the left and right units within a single digit percentage tolerance. I thought i read online somewhere it was around 3-5% variability/tolerance, but i would have to verify that.
On the other hand, i read people here are super happy with their H&R springs, so YMMV.
Like you, i do not plan on taking my car to the track, so some of the features that come along with higher-end coilovers like kW was not worth the $2k-$3k price tag in my opinion. BC Racing BR-type coilovers were meant as a solution for mostly street use with occasional track duty so it was perfect for me.
Overall, i love the decision going with coilovers and i'm really glad i went with BC. The construction and quality of the materials of the unit is top-notch, and the ride height variability over springs only, along with a 30-setting damper setting adjustability made the choice easy. Plus i love the black and gold color combo of the unit. It rocks
even though you can't see them most of the time, i'm not a big fan of the weird neon-type colors used by some of these CO mfgs. But that's just me.
I haven't gotten a chance to experience the whole range of damper rates yet. There are 31 clicks on my coilvers that i could manually count. They are currently set at 24 (0 being softest and 31 being hardest) and they are fine. With how low my ride is set to now (I have about 2" clearance from the ground) i need it more stiff to compensate going over bumps/dips without taking out my exhaust. Still, its soft enough that i can't tell the difference between stock and coilovers. However, the roads here in the SW part of Arizona are pretty good, so maybe its not a fair comparison.
The only thing i hate is that there is no clear documentation for how to adjust the rear ride height. The quality/construction rocks, the adjustability rocks, the colors rock, but the documentation just simply blows balls
They have an North America division of BC, but the instructions are written by someone whose first language is clearly not English. With how much business they do in the US, i'm surprised they don't just get one guy and have him take an hour and re-write the damn thing clearly so the rest of us US customers can make heads/tails out of the instruction manual.
The ride height adjustment for the front is easy as pie (takes about 5 mins to adjust after getting the wheels off), and you don't have to mess with the spring pre-load. Its just loosening one lock ring, then turn the ride height adjustment collar up or down to suit your tastes, then re-tightening the lock ring. The rear however, is a royal PITA. You actually have to mess with the spring pre-load and as i have up in another post, i'm wondering if i need to detach the control arm as well. I should be fair and state that i believe most other rear coilovers will require the same thing. I don't believe this is a BC-only limitation. I think someone needs to come up with a brilliant innovative way to adjust rear ride height wihout have to mess with the shock height, spring pre-load, control arm, or any other part of the suspension. There's a huge opportunity there...
Oh, the other thing i hate is that the damper settings for the rear require you take off the rear wheels. That's the other PITA thing with BC coilovers for the F30. For some cars, they offer rear extender controls that can feed up either into your truck or rear cabin seat area. So you can adjust damper by just opening the trunk or getting into the back seat. I heard that some owners complained to BC that they didn't like the fact that installers were drilling holes through their seat area or trunk area, so BC discontinued that for some cars. Apparently for BMW that was the case. I would rather drill one tiny hole to get at the damper settings rather than have to take off the wheel, but again, that's just me.