  Architectural decision-making is a crucial concern for researchers and
practitioners alike. There is a rationale behind every architectural decision
that motivates an architect to choose one architectural solution out of a set
of options. This study aims to identify which categories of rationale most
frequently impact architectural decisions and investigates why these are
important to practitioners. Our research comprises two steps of empirical
inquiry: a questionnaire (63 participants) and 13 interviews. As a result, we
obtained a set of rationales that motivated architects' decisions in practice.
Out of them, we extracted a list of software quality attributes that
practitioners were the most concerned about. We found that, overall, architects
prefer to choose solutions which are familiar to them or that guarantee fast
software implementation. Mid-career architects (5 to 15 years of experience)
are more open to new solutions than senior and junior practitioners.
Additionally, we found that most practitioners are not concerned about the
quality attributes of compatibility and portability due to modern software
development practices, such as the prevalence of using specific standards and
virtualisation/containerization.
