AT Opus 1

The answer is Opus 2, obviously.

Agree very strongly with @tablejockey in that the quest for the one grail cartridge to rule them all is not very productive… but if you want a higher performance Lyra why not seek out the Lambda low output version of what you have ???? 
@jcarr.        Sometimes visits here perhaps he will weigh in

I've also owned top tier Lyras and had a couple Airtights and when I was looking to upgrade from an Airtight Supreme, considered the Opus which is a fine cartridge, but went in a different direction- to Koetsu stone bodies. Those work better for me given certain system parameters but I would not say they are "better" cartridges- instead, the low compliance is more compatible with my air bearing linear arm (Kuzma Airline); the tonal balance is better suited to complement the strengths and weaknesses of the rest of the system (Avantgarde Duos which can be bass-shy without supplementation); and a subjective preference. 

I've heard direct controlled comparisons of some of these cartridges and it is a difference of shading in some cases if all else in the system and room is optimized. 

Good luck, nice choice to have. 

Burmester 175 

Looks the part for a super high end cartridge.

That system looks like it sounds pretty good too.