I don't really understand why this question comes up very often?
-- every company has high profile projects and low profile projects. Some are more mission critical than the others.
-- cultures and technologies used can vary from team to team within the same company depending on --> it was a new application or an enhancement to a legacy application.
-- Management style can vary.
-- There are many other factors.
So, rather than blindly looking at Company X or Compan Y, Think in terms of Job A or Job B
use your interview process to ask the right questions
-- Nature of the project --> new versus existing, mission criticality, team size, etc
-- Technologies and frameworks used.
-- Your role and responsibilities -- lead development, support, design and development, mid level, senior, etc
-- Opportunity to integrate with other systems, etc
-- Development processes used -- waterfall or Agile.
Once you have the answers to the above questions, you will be in a better position to assess the possition and see how it aligns with your career objectives and aspirations.
-- Ascertain what skills you already have, and what new skills you would like to acquire? Is this new position conducive to acquiring the required skills?
-- Ascertain what new technologies and frameworks you would like to learn next? Will I be using these sought-after technologies and frameworks?
-- Ascertain where you like to be in next 2 years, 6 years, etc? Progress to become lead developer or a team leader.
You can always research a company and their business acumen by googling, checking the company websites, and networking.
Choosing the right job is one of the key and most difficult career decisions you will have to make. So, please use your pre-interview preparation and the interview process to your full advantage to decide what is best for you. Don't let recruitment agencies or others choose what is best for you. I alwys hear recruiters saying, this will be an ideal job for you. Every one is different. So, you will be the best person to decide what is best for you? If you still can't make your mind up, talk to your mentors or forum experts for their views. Provide more information about the position, requirements, your career aspirations, etc. Don't just say "Company X" or "Company Y".
check my blog entitled "How to choose from multiple Java/J2EE job offers?" at http://java-success.blogspot.com/
for some tips and hints.