Once you are set to pursue academic research, you may have a few options regarding labs and PIs you would like to work for.
While this is a very coarse view on how labs function according to their “size,” with exceptions in all kinds, I have observed that many of those characteristics are shared within labs in the same category.
The “Big PI”s lab is an obvious temptation to all early career scientists, most especially those who want to be able to say “I had my training in Dr. X’s lab, a Nobel Laureate”. That desire usually comes along with aspirations of glossy publications, and generous job offers, once the training is complete.
In a lab like this, usually, money will not be an issue., Grants will continuously flow in, and you will be able to access all those fancy machines and latest techniques. If you play your cards right, you may be able to do whatever you want as a side project. Many people may want to collaborate with you for a taste of those same things, while having your famous PI’s name ease their way into a glossy journal as well.
While all of the above can certainly be true, they may come with a small print: Those world-known PI’s can be extremely busy and almost unavailable. If you are completely independent, that may not affect you, but keep in mind that aside from a boss, you also want a mentor.
In some cases, while trying to boost productivity such as getting galactic publications as fast as possible, they may throw ideas around, and whoever picks them up first, races their way to the bench and makes it happen, is the winner and will be the one who gets to publish it. Those less fortunate who joined the race but didn’t win, will be pushed far away from first authorship, and closer to oblivion.
That said, the environment can be tense due to competition. Lab meetings can feel more like an arena. People will mostly focus on their own things, not collaborating/helping much within the lab.
Needless to say, this is a system that may lead people to break down. This may also lead to desperate measures such as having to include lower accuracy data, leading to shameful paper retractions from those same glossy journals.
So the take home message is: If you are already extremely well trained, and can handle well stress and competition you can thrive in a big lab like this.
The alternative is a medium/smaller lab
The PI is usually younger and less famous. Because of that, he/she may remember better their time at the bench, which is important because they are more likely to be able to put themselves in your shoes.
They know the techniques you have to use, and can guide you better when you need to tweak things. People tend to really collaborate and help each other more, and skills are passed on to newcomers. You will realize that the lab is more budget-conscious, so there can be times in which you will not be able to buy that mega expensive reagent, but you may have access to someone who can give you an alternative cheaper protocol.
Also, since you are not constantly racing to the bench, you may take the luxury of enjoying semi-normal daily work hours and even weekends. You may have to settle for a lower impact publication, but it may be one that is actually cited for the right reasons, because people are able to reproduce your data. If you would like to work in a lab that will provide you with a friendlier atmosphere, with a more accessible PI, and a better work/life balance, this may be a better choice. It may require you more efforts to reach a high impact publication, but you may be happier overall, because your lab stress is more manageable.