A few mainstream kit suggestions:
The newer AMT 57 Chevy is a real nice kit as the early 60's Pontiac released a few years ago. The 68- 69 GTX/ Roadrunner is also decent, though AMT also has moulds for the Daytona's that maybe go back to the MPC days (not as much detail)...someone will correct me if I have the wrong lineage, there. The AMT '62 T- Bird looks like it will be a decent build- I am just working on it; the '57 T- Bird is a much older and lower detail kit. The '57- '58 Plymouth/ Chrysler kits from AMT also have nice detail.
From Revell, the '48 Fords are nice, the late 60's Charger in the same program is also nice. The late 60's Dart is a really nice kit, too. Not as familiar with Revell stuff, but I really enjoyed building the above mentioned kits.... the '57 Checy and the early 60's Pontiac were the biggest surprises as I am so tired of the ubiquitous '57 Chevy...lol... but it was a lovely kit...only built my copy because I got it at a yard sale for $2 or $3 and will build another when the chance presents itself.Also liked the '67 GTX kit, though it is not as good as the '69 Dart.
AMT also makes a '62 Chevy (I think it is a '62) that has decent detail, far superior to the older '63 that was part of the Prestige series...Corvettes by both AMT and Revell are all over the place in terms of detail... the one by Revell that is part of that better series that offered is really nice to build, but the AMT '60 Vette and the Revell early Vette ('53?) are not so detailed.
Lindberg is a hard outfit to figure out...the '32 Ford they offer is fun to build though not super detailed, and people raved about the '53 Ford and the '64 Dodge...I found the latter two not as enjoyable because of the fit was tricky in places, though the '53 Ford convertible turned out fairly nice.
I am partial to Mopars, and the Fords from the 30's to the late 50's....while they have some limitations, the early 50's Ford, the '49 Merc and the '57 Ford have been around forever, but I have built several of each, as they are fun to build, and fun is what it is all about, for me... my "big" unfinished project is a '68 Plymouth ragtop rebuild...the '68 Plymouth ragtop consists of a beat (smashed windscreen area) Johan promo, since repainted nicely but in need of a windshield frame.... I cut open the hood. The chassis and drivetrain comes from the '69 Charger I mentioned, from Revell, as the detail of both the chassis and motor are quite good. The interior has to be the original interior, as the Charger interior, besides being incorrect, was just a bit off and did not look "right", so the Jo-Han interior got a repaint and will be the weak part of this project. I cut the windshield area out of the Charger body but it just did not look right... will eventually find a "more correct" windshield and frame for this project, and when it happens, it will get finished....the Charger frame had to be shortened something like a sixteenth of an inch and looks good with the Jo-Han body...has rallye wheels, too, which look good. I also have to get the rear bumper and front bumper/ grille replated.
Bill