depends on a lot of of stuff.
depends on the ping the server is getting, your ISP, router, modem, wifi adapter, etc.....
if u can do wired, go for it. if not, then get yourslef a good wifi adapter.
heres my results. note- my wifi adapter on my laptop is only G speeds, so i dont get the full download speed. note- on my desktop N adapter, i get exactly the same speeds download, and slightly slower uploads. about 5mbps slower.
there are 2 types of ping on ethernet, you to your ISP, and ISP to server
there are 3 types of ping on wireless, you to your router, to your ISP, to server.
like i said, my wifi adapter is crap on my laptop, its always trying to save power and reduces its speed. but what i want to show you is ping. on my desktop, i notice 0 difference between wired and wireless. the only thing i do notice is slightly faster dl speeds in steam.
pic 1 - wireless to my router ping
pic 2 - wireless speed test
pic 3 - wired ping to my router
pic 4 - wired speed test
again, speed is limited on my laptop because of the adapter in it. i get exactly the same speeds and pings on my wireless desktop.
so yes, wireless is not as consistent as wired, however the result is only 1ms ping in real world games. a friend of mine play games together. he has 10x better internet than me and is on a wired connection. im on wireless. in games, i usually have less ping then him by 1-5ms; and he's rite next door to me.