Evaluate their websites:
In their online career sections:
Do they have career channels or playlists on YouTube? Job listings on Facebook?
In job ads:
Search "your company name" AND ("job fair" OR "career fair") in library databases like NexisUni and Factiva to find career fairs in which your company participates.
Check the career sections of major business schools: Does the company seem to have a relationship with these schools?
Search for company recruiters (or similar positions, like "talent acquisition") on LinkedIn and see what they say their jobs entail. There may be information about campus recruiting activities, job fairs, or other recruiting activities.
If you had to apply for a job at one of these companies, which one would you want to work for? Why? How much of your answer is based on information the company is providing via its website and job ads? (i.e. has their recruitment PR worked on you? why?)
Vault Career Services is an IU Libraries-provided database that discusses, in part, the recruiting/interviewing practices of companies. It has better coverage for some industries, worse for others. Also check sites like Glassdoor, Indeed, and job-applications.com to get some perspective from the potential employee side, but USE CAUTION HERE: These sites can attract those with an axe to grind. Use what you find to make inferences about the recruitment and interview process, but don't assume that all complaints and characterizations of people and experiences are accurate.