I know there are a few posts about this already, but none of them have given me definitive answers as to whether I should go with one or the other. So I'm deciding between a 95 SC300 and an 01 IS300, and I'm conflicted as to which one to get.
Both are very nice looking cars, as many of you know the SC has aged very well for a 90s car. Both also have more or less the same engine, but I've heard the IS300 might have weaker rods that may not withstand boost as well due to it being VVTi.

I like the SC300 because it's a coupe, it's pretty uncommon to see in the wild, so I'd love to have a unique car that I can wrench on and mess with. Since it has a 2JZ, it has a lot of engine mods I can do. Other mods may be more difficult to come by, like the exhaust system, coilovers, brakes, and so on. Parts may not be super easy to come by either. It also weighs more than an IS300 despite being a coupe. The interior according to the net is also way nicer than the IS300.
I like the IS300 because it's lighter, has a 2JZ that I could still build on, and it has great aftermarket support beyond the engine.
My goal is to have a nice, daily-able car that I can build to be fast, but also handle really well in twisties and backroads and just be really fun to drive in general. I may or may not have passengers, but I probably wouldn't take more than 1 person in the IS or SC. I have a V6 Camry that I daily so that's still my grocery getter. The IS/SC will be my secondary that I'd like to drive to school/work or go out on the weekends for fun with a friend. Being able to drive it daily is NOT a requirement, but it would be nice.

 

Have SC300 for few years and just bought IS300 this month.
SC300 is 1JZ-GTE though, think it's more common then 2J. Have it for few years now, didn't drive to much as daily as it's a skid car (and is old in general - used e90 as my daily). It's sitting in the back burner for a while... as it's big and heavy (doors must weight 30kg's . and didn't finish my rollcage yet ( should listen to the old saying: "don't deep dive into long term project, just drive the car...").
Reg. parts availability, anything from MKIV supra works (except body panels), so... it's pretty big aftermarket support mate.

Bought IS300 for a low-budget / cheaper skid car than SC and my 350z ... Will tell you in few months how is it to live with it.

 

I own both an IS300 and SC300.
The IS300 is a better car to drive daily and to drift. It is physically shorter and easier to get in and out of. It weighs 200-400lbs less. It also is cheaper to insure and has a lot more OEM parts still available for it. Having 4 doors, it also has a lot more room to carry stuff.
There are 2 weaknesses that I know of that the car has.
1. The VVTI motors have weak rods and pistons. If you want to put down more than 400ft.lbs of torque these have to be swapped out. If you find an original 5 speed IS300, those have W55 transmissions and they pair with the VVTI motors perfectly because those are also weak transmissions that are known to break at the same torque level that bends rods.
2. Because the cars have a shorter wheelbase, and its overall shape, the cars become dangerously unstable above 120mph. These cars are prone to crashing because of that and they do have a history of killing people who disregard this fact. You don't find a lot of high horsepower IS300s for this exact reason. Once they get to about 600whp, owners tend to stay there or leave the platform for something else that's more stable at high speeds and higher horsepower.

SC300s are cool. They can be found cheaper than IS300s but they tend to have lots of problems associated with old cars that have been neglected or owned by people who can't really afford to keep them. The cost of owning a SC is roughly 2x the price as an IS. There is no shortage of engine parts, but when it comes to aftermarket parts, there is 1/4 of the parts out there than there is for the IS300. There is no OEM aftermarket for the SC - in the event that you have a bad balljoint, you need to buy performance aftermarket suspension arms. And since almost all the suspension of the car is shared with the JZA80 Supra, what pieces are available are priced accordingly. We call it the "supra tax". If you are looking for OEM Lexus parts, such as interior panels, 90% of those are long discontinued. SCs are a big car, longer than a GTR, but interior wise they don't have a lot of room. The rear seats can fit 2 car seats and thats about it. The trunk is big and deep, but it would be a lot bigger/better if the gas tank wasn't behind the rear seats IN the trunk next to the rear firewall. This makes for great weight distribution but gives you a car with the trunk space of a old Corolla.
Because SCs are becoming so rare due to attrition, a lot of us with nice ones don't drive them everyday. For some strange reason they seem to attract more than their fair share of accidents, and with them even a minor accident can get the car totaled out.
My SC is my fun weekend car meet car and my IS is my fun daily driver