I like the EVM-12L. I acquired one by accident (in a trade well over twenty years ago), and it has become an integral part of what I identify with.
The EV stands out as keeping it's composure (some say stiffness/sterility...a valid point) from the lowest volumes, until the amp cannot give ANY more.
They are a perfect match for Mesa combos, as there are few individual speakers that can take the push from an open back 1x12 100 watt Boogie combo. Mesa is the known for extra gain, and one of the best attributes of the EVM-12L is that it quenches "fizziness". Mesa could have always used a less expensive speaker, and pocketed the difference...but they put the best speaker they could find with EV's. The reason why EV's are not very popular is directly related to the cost, and secondarily the weight. BTW, these speakers NEED to be attached by more than four nuts/bolts.
I have used the EV with 6550's and 6L6's. A person needs to like their guitar/amp tone before they mess with EV's, because EV's are not going to have a particular "sweet spot". It is simply a speaker that refuses to get pushed around, yet the high efficiency gives you all volume you need.