As a rule of thumb I'd think of places that have more than just one main guy who has success.
For example, McGregor is a very good striker but i'd be fairly confident in saying most of that is from McGregor himself not necessarily SBGi, and could probably find success most anywhere.
As to the question i have a few thoughts. One thing that jumped out to me before and after the Khabib vs McGregor match, was how people sometimes forgot that American Kickboxing Academy started life out as... a kickboxing academy. They are most known nowadays for all the good wrestling based fighters they have (i would say that is simply a reflection of trends of what works best in mma though), but all of them know how to handle themselves on the feet, including and even the more dedicated ground fighters like Khabib (as we saw in the Iaquinta and McGregor fights).
There's a few other places that come to mind with regards to striking;
Kings MMA has had guys like like Werdum, RDA, and Kelvin Gastelum as stand outs.
Ricardo Almeida Jiu-Jitsu might be a surprising name to hear, but they have guys like Frankie Edgar, Eddie Alvarez, Marlon Moraes, and Zabit Magomedsharipov.
ATT has produced a lot of guys with good striking, from JDS, to Yoel Romero, to Robbie Lawler, to Douglas Lima, to Tyron Woodley, to Santiago Ponzinibbio, to Albert Tumenov, to Dustin Poirier, to John Lineker, to Jussier da Silva, to Kyoji Horiguchi.
You know if i were to look up a list of successful submission/ground fighters, a long list of those names would happen to also be from ATT. In my opinion they've been the best organization in the business for a while now.