When first starting out every coder has the same question. Who should I work for in order to better develop my skills? Is a bigger tech company best or is a smaller startup the way to go when first starting out? The reality is that no one can give you a good answer to that question except you. The answer depends on what you want to get out of that first job and what kind of things you want to learn and experience.
There are a few questions that you need to ask yourself prior to starting out that will give you better insight into the right company for you.
What skills do you hope to hone? What Would you like to learn? If the answer is leadership then you will probably have more chance and better opportunities if you are working for a smaller company that is just starting out. The larger companies have leaders already in place and most of them have more leaders than they really need.
If, instead, you want to learn more about how to code on large, multifaceted products and/or learn to develop a product roadmap, the answer may well be found in the larger tech giant. These larger companies typically get more of the really big projects that take a longer time to undertake. If you want to learn more about big business then a tech giant is the way to go.
What drives you? If you like to roll out big ideas to your customers in a really short time, the smaller startup is the way to go. Bigger tech giants like Microsoft or Google will take months to roll out your idea, while a startup may help you to do it in a week.
What do you want to learn at your first job? What is the right environment for you? How do you operate best? In a structured environment or a more loosely structured one?
Once you have all of the answers to those questions will help you to determine where you want to work and what is the best way of working for you.