Pop is the lyrical zenith of Bono/U2's career. The only other record that can compete is AB. Bono is more sincere and from the buring, gut-wrenching, bitter soul in songs like Mofo, If God, Gone, Please, and WUDM than anywhere else in the U2 catalog save for 'One' and 'Acrobat'. If God and WUDM are scathing lyrical commentaries on God and whether He exists or not, and why He lets shit happen. Mofo and Gone are candidates for Bono's most personal confessional ever. Staring At The Sun and Please are some of Bono's finest political pieces, Please also being one of U2's best ever songs. DYFL is just dirty and brilliant. LNOE tells a story in and of itself to which there are different interpretations. Etc etc etc.
I'm not saying that ATYCLB is lyrically bad, I actually think it's underrated in that department. But lyrically nothing beats Pop.
And musically U2 did things sonically on Pop they never did before or after except for maybe AB. The music is lush and creates soundscapes, worlds to explore with your headphones.