[GTALUG] router upgrade

Greetings I've been running an Asus rt-n16 router, using dd-wrt, for about 6.5 years now. On the second one for about 1.5 years and no longer have a spare for the next time the router craters. Am finding it very difficult to determine an update/upgrade for my router. Any suggestions? (Trying to keep the costs down too, please.) Regards Dee