I replaced my old D-Link Draft N router with a then-current generation simutlaneous dual-band Airport Extreme in February, and then I replaced my cable modem last month. I think that I went from about 10 MBps down and 1.5 MBps up with the old setup to about 15-20 MBps down and 3.5-5 MBps up, depend on traffic on my Comcast internet service, and I didn't even upgrade the plan. The 8-year old old Arris modem was locking up, which is why had to replace it.
Back on topic, probably just about any new router would be of help, but despite the price the AEBS is probably one of the easiest to setup.