Depends on what you like.
You'll most likely go with a keyboard featuring CherryMX switches, so you should probably check out
Cherry's website.
You can click on the switches on top to "navigate through the switches" to list off their stats.
A lot of people prefer CherryMX reds due to their low activation force, making them take a bit less stamina, while some people need the feedback of CherryMX blues / browns to know that they pressed the key.
It all comes down to preference. I'd advise you to go to a local store and test out the different switches.