It really depends each have their great kits and their crap kits. Also auto modeling was one of the first and there are many re-issues of kits first seen in the 60's along with the common metal axles, indifferent detail etc but also the only kit around of the subject. In this respect it is a little like armor, the way many of the older Tamiya kits were designed for electric motors.
With autos subject matter is often what determines who you get the kit from. Its not like armor and aircraft where you may have a choice of several kits from a couple of manufacturers.
In general the Japanese kit makers have the best reputations, Tamiya in particular, but they also do more curbsides than the American kit makers. They also tend to be focused on Japanese and European cars. If you want a detailed motor or an American Muscle car you will usually have to go with one of the American companies.
Tamiya kits are fantastic, I just got their Alpine 1600SC, I could almost just lay the sprues on the shelf and call it done.
AMT / Ertl has some very nice truck kits, also many good 50-60's era cars. They also have numerous re-issues from the 60's-70's which are very bare bones kits. Not bad if you know but many complain when they expect full detail and they get something similar to a well detailed dealer promo. AMT / Ertl has many nice big rig kits.
Revell also has many good kits. Monogram is part of Revell, sometimes the kit shows Monogram sometimes not. In general Revell / Monogram kits are very nice.
Italeri and Revell Germany share many molds, so you find many similar kits under either brand name. You also find this with RoG and Revell. From my experience these are nice kits, but most are European vehicles except for a few American big rigs.
Lindberg came under new ownership last year and seems to be doing quite well. Lindberg has many old kits from other manufacturers, some of these are good some not. The 1934 Ford pickup is an ex AMT kit and is very nice, the Auburn, Cord and '48 Lincoln typically make the 10 worst kits ever lists. In general most Lindberg kits are decent to very good. Again they offer some unusual kits, the Dodge A100 pickup and L700 big rig being good examples.
Johan is on life support, technically it is still in buisness but the owner is struggling, so you usually have to get them on ebay or model shows. The kits tend to be fairly basic but they make up for that in options (many are 3 in 1 or more kits) and unusual subjects.
Heller and Airfix have about the same reputation as they do in other areas, some good some bad but mostly you get them because nobody else makes a kit of the subject.
MPC was absorbed by AMT / ERTL in the 80's, you can find these kits under the AMT brand or the MPC brand on occasion.