a good place for MIP solver comparisons (including expensive commercial solvers like Gurobi and CPLEX, as well as other commercial and open source options) is Hans Mittelmann's website:

http://plato.asu.edu/bench.html

here are MILP current benchmark results (updated this month) including CPLEX and Gurobi

http://plato.asu.edu/ftp/milpc.html

If you are interested in which is the best (fastest? finds feasible solutions most often?) solver for a particular kind of problem, these general benchmarks perhaps don't matter as much - you need to compare the solvers on instances of your problem.

edit: i think it is possible to get free trials of commercial solvers if you are interested in trying them on your problems. Gurobi also appears to have a cloud offering where you can pay to rent a solver for a short time.

Thanks for the help. My company uses CPLEX in production on some massive models with a lot of constraints. I'm always curious if Gurobi would be better, but I'm not sure how much work it would be to port it to run on a trial version of Gurobi on the same hardware.

Edit: What are the numbers in the links provided? Number of solved cases or time?