There's a few things I would generally look at in a potential advisor beyond just their research/publications:

• Who were the co-authors on their papers? Are they actively collaborating with people in your field - people who could be potentially useful for post-doc posts, etc.? Do their students often show up as primary authors on publications, or are they invariably buried in the middle of a long list of authors?
• Personality. This goes beyond just do you like the person. Do they prefer frequent updates, meetings and the like, or is the occasional check-in enough? Are they a morning person and you prefer working nights, or the other way around? If you send a long email, would it get answered, or do they not often fail to answer emails? I've had some professors who I'm very fond of never the less would make poor advisors because of wildly disparate working styles.
• How are their students funded? Your funding stream can have serious impact on your completion time and productivity. If every semester its a desperate Pick-N-Mix of funded side projects, TAships, etc. you're going to have a lot on your plate that, while potentially an interesting experience, will slow down your progress.
• Where do their students end up? Do they have decent career trajectories? Are they supportive of alternative paths like industry or government?
• Rank and age. A young professor might be more aggressive and eager, on the other hand they're less established, don't necessarily have the same level of institutional support, and if they're not yet tenured, its possible they'll disappear. An older professor may be more established and stable, but might not use "cutting edge" techniques, or feel less of an internal drive to publish.

There are a few things I would generally look at in a potential advisor beyond just their research/publications:

• Who were the co-authors on their papers? Are they actively collaborating with people in your field - people who could be potentially useful for post-doc posts, etc.? Do their students often show up as primary authors on publications, or are they invariably buried in the middle of a long list of authors?
• Personality. This goes beyond just do you like the person. Do they prefer frequent updates, meetings and the like, or is the occasional check-in enough? Are they a morning person and you prefer working nights, or the other way around? If you send a long email, would it get answered, or do they not often fail to answer emails? I've had some professors who I'm very fond of nevertheless would make poor advisors because of wildly disparate working styles.
• How are their students funded? Your funding stream can have serious impact on your completion time and productivity. If every semester, its a desperate Pick-N-Mix of funded side projects, TAships, etc. you're going to have a lot on your plate that, while potentially an interesting experience, will slow down your progress.
• Where do their students end up? Do they have decent career trajectories? Are they supportive of alternative paths like industry or government?
• Rank and age. A young professor might be more aggressive and eager, on the other hand they're less established, don't necessarily have the same level of institutional support, and if they're not yet tenured, its possible they'll disappear. An older professor may be more established and stable, but might not use "cutting edge" techniques, or feel less of an internal drive to publish.