I don't know what wireless card is the best, but I am certain it would be way better than a USB dongle. I have a USB dongle on one computer and it's terribly slow. Our laptops are reasonable, but still slow.
I have 2 routers, a high power buffalo router and an asus router. Both routers have Tomato firmware and aftermarket antennas. I use the buffalo router as my main WAP and the asus is setup as an ethernet bridge next to my TV, so my PS3 and whatever laptop we have hooked up to the TV (soon to be my shiny new HTPC) gets plugged in to it with an ethernet cable. My throughput typically doubles when I go through the asus bridge vs built in laptop wireless.
That might be a little much for just wanting a wireless adapter, but it works great for me.
My routers seem to be quite good, almost everything in my house is wireless (PC, Laptops, PS3, etc) and there seems to be no problem with it at all, however a lot of people seem to say that there is a big difference between wireless and wired internet, but whenever I plug my laptop in via ethernet I notice no difference at all.