What is the best alternative router firmware these days? The last time I looked into this, I believe it was between DD-WRT and Tomato.
DD-WRT hasnt had a stable release in 11 years. Tomato hasn't had a stable release in 9 years. OPEN-WRT is a fork of DD-WRT. Lede was a fork of OPEN-WRT, but has remerged with OPEN-WRT. OPEN-WRT is the best firmware for home routers/access points in my opinion.
FYI, tomato has a still kicking fork: