Wifi, directly to the router I get the full connection.
I personally prefer wired internet using Cat5e or Cat6 cable, check which one your router supports. If it's a desktop, just use wired because it's inexpensive and you get much faster speeds. Also, what did your ISP promise for download and upload? Also, downloading a large file slows it down, and if someone else is gaming or using bandwith, it also slows down the internet. If you're using a laptop, honestly, just build a workstation and connect a cable to it.
I hope this helps