Hi, I think I am in the same boat as you, late 40s with unilateral cataracts in my right eye. I think you are in a little better position since your left eye is only -3D, mine is -5D. I found it also very difficult to decide on the lens and focal distance as whatever I do to my right eye now it has to work in the interim when my left eye is still okay at -5D and also after the inevitable cataract surgery to my left eye who knows how many years later.
So, the first question is - Can you wait? There are always new technologies coming out every year, especially in Europe. My suggestion is if you are going to wait and see, at least go to a good cataract surgeon and take all necessary eye measurements first. In my case I waited too long and the better instrument cannot penetrate pass my matured cataract and need to settle with less accurate ultrasound measurement of my eyeball length. Lucky it turned out okay.
Also, ask your optomologist to let you try monovision, or a -1D prescription on one of your eyes. You can see how blury distance vision is when your eye is set for -1D ( or something like -0.75D). That will help you decide if you want to set the focal length to intermediate distances. Same applies to monovision. You want to try that before your right eye is too blurry to see.
As you must have know now, you have to choose between monofocal iol and multifocal/EDOF iol. I asked myself what drives me more crazy, having to carry and switch between glasses all day or seeing a permanent, uncorrectable Halo and starburst at night.
One thing you need to keep in mind is something called Anisometropia. That is having a significant difference in reflective power on your left and right eyes. If you set for Plano on your right eye, you might have problem using spectacles (your left eye is -3D, right) and need either to wear contacts or Lasik on your left eye. That is one reason I suggest going to your opthamologist and ask him/her to give you a contacts for your RE and see if your are okay seeing thru your spectacles with the right lens popped out. If you can get used to it, you might be able to avoid Lasik all together.
For your reference, I choose toric monofocal for my RE targetting -1D and wear contacts on my LE. LASIK on my LE is an option too but I will wait to see how the cataracts on my LE is advancing. When the time comes for my LE, I will do monovision with 0D. My RE turned out to be -0.7D after surgery. Now my RE's best focal distance is my armength. Computer vision is superb, crisp, clear and color is vibrant, couldn't believe it. I guess I have forgotten how excellent my vision used to be. Using my RE only I can see my phone fine as close as uo to 12 inches without any aid nor bigger font sizes under normal lighting conditions. Reading distance object is more difficult, but at least I can drive without much problem in the day time. I need to wait until they are closer before I can read the street signs, and I cannot read the licence plate unless the car is right in front of me. But that is a compromise I knew in advance. Again, all I am talking about using my RE only. Together with my LE everything besides reading very fine print is from good to great. I will get a pair of distance spectacles later for driving. I probably need readers too, but no immediate need as I can use my -5D LE for up closer vision when I am not wearing contacts.
Hope that it helps.