Welcome to CL as a new poster.
Buying new tires is not a just a crap-shoot. You need to look at your specific driving style/needs, determine what are priorities be willing to accept the trade-offs that each tire (or type of tire ) will give you, and work from there.
Although new formulas and advances in rubber and silicone-compounds have greatly lessened the compromises one has to make today in tire strengths and weaknesses, in general, tires with softer compounds will give you more grip (meaning better handling. braking, acceleraton, etc....) at the cost of more rolling-resistance, faster tread-wear and earlier replacement. Summer-only tires excel at dry-weather handling, but are very poor in winter condtions on icy roads....and will usually also have rapid tread wear. All-season tires are usually the best choice for most people...they perform reasonably well in all conditions, but don't really excel at any one......though there are some brands of all-season high-performance tires. Rain tires, of course, have tread patterns that resist hydroplaning, and winter/snow tires have tread-block patterns that maximize snow/ice grip, but are often quite noisy and wear quickly. Low-rolling-resistant tires have rubber compunds that ease the work on the engine, making them ideal for hybrids and other gas-mileage-oriented vehcles, and they have good tread life, but road-grip and handling can be sub-par. Lower-profile tires sharpen up steering/ handling at the cost of ride comfort (sometimes with quite-stiff rides). Higher-profile tires generally do the opposite....add cushiness to both the ride-comfort and the steering. There are also diferent combinations of the types mentoned above.
In general, no matter which specific type of tire you choose (or need), despite its popularity with the aftermarket/customizing crowd, I do NOT
recommend deviating from the original factory-installed size without doing a lot of other things to compensate. The electronics and sensors on your car were designed for that specific factory tire-size, and deviating from it can give erroneous readings for both the speedometer and odometer...in some cases, voiding the warranty (though your IS300 is probably close to or out of warranty by now). Still, an false-reading speedometer can make speeding tickets easier to get, and a false-reading odometer violates Federal law.
As far as specific tire brands go, Michelin has a long-standing reputation for making some of the best, (and also some of the most expensive), but other brands, such as Continental, Pirelli, Goodyear and others, have been catching up in both quality and price. Some tire-brands also excel in one type of tire, but not in others.
Here's some info that will help you when tire-shopping. By law, tires are usually labelled by size on the sidewall, with a (sample) being P225/50R-17. The P means a regular passenger-car tire (as opposed to truck/off-road/motorcycle tires). The 225 means the tread-width in millimeters. The 50 means the sidewall-height compared to the tread width (in this case, 50%) The R means radial-cord construction...as virtually all new regular car-tires are. The 17 means 17 inches for the wheel-diameter it fits on.
Hope that helps.