Got it. Definitely start off giving 5Ghz a chance first. If you plan to get a new wireless card, I suggest looking at an 802.11ac card with external antennas, if you have a desktop. The internal cards with antennas have better performance and range, and have less of an impact on CPU usage. They typically install into a PCIe 1X slot. The USB dongles do their job and are easier to plug in and use, just be warned that their antennas are not always fabulous.
In a laptop, most have swappable Wi-Fi cards. If you're comfortable doing so, replace the WiFi card in the laptop with a compatible 802.11ac card. Typically these cards are located in the same spots as the RAM, or have their own access door.