Every company has a unique culture. Some companies are rigid when it comes to rules and others are quite lenient. One of the main factors that determines what it is like to work in a particular company is its size.
Large corporations are often more systematic. There is an HR Department or a Personnel Department that puts in place policies and procedures. Due to their size they can also usually cope with people on maternity or long-term sickness leave without too much impact on the business and the other employees. You can expect to have more job security at a large, established company.
On the downside, larger companies tend to have a one-size-fits-all attitude to employees. There will be lots of rules and regulations and some people find this stifling.
If you like variety and hate bureaucracy then a small company could be right for you. You will have a more personal relationship with the boss and with your manager and this will allow them to be more flexible with the rules. A lot of small companies have a family-like atmosphere and a relaxed working style.
However, there will be days where you wonder what your job specification actually is. In a small company, everyone has to pitch in and help. A small company may not have a marketing department or a team of secretaries, so you may end up doing tasks that are way outside your job scope.
So which is best: large or small? The answer depends on your personality.