Most of the pages on this site are witten with as little bias as possible. However, if you are looking for a personal recommendation from the author of this site, you've come to the right page!
SeaFoam
On top of having multiple uses, SeaFoam is really good at every use it is designed for. Its most common use is a fuel treatment; it can remove water and contaminants from fuel (gasoline or diesel) and clean out the fuel injectors. It can also be used to flush the engine, or dripped into the intake while the engine is running to clear out carbon build-up from the intake and exhaust.
Brake Parts Cleaner
A number of companies produce this, but even the cheap kind is able to blast away dirt and sludge that builds up in vehicles and their components. It can be used to clean oil pans (inside and out), engine blocks, suspension parts, and almost anything that has oily deposits on it you want removed.
Note that brake parts cleaner can dry out rubber, which will at the very least leave the rubber looking old and oxidated.
Royal Purple Oil
Royal Purple synthetic oils are high performance, long-lasting oils that can take quite a bit of punishment. Ever since Steve started changing his own oil, he has been using Royal Purple oil.
CRC Sprays
CRC produces a number of helpful chemicals that a lot of other companies don't distribute or produce much of.
CRC's belt conditioner spray helps serpentine belts last longer and reduce slipping. It also doubles as a rubber component restorer which can add shine back to old components like air intake tubes.
Wiper Blades
For wiper blades, Steve recommends both the Trico Onyx and Bosch Icon wiper blades. They are beam-type blades which last longer, produce less drag, look better, won't shake at high speeds, and do a better job of removing things that shouldn't be on your window.