Myself I would always go cab because whilst the speaker/room chain and such is great I just love the natural cab tone, cant beat a real v30 imo.
And there's a sizeable contingent of people that feel this way.
But also bear in mind that when each amp is developed, same with every pickup, it's made for a specific speaker and cab. In other words, if your cab was designed by Rivera for Vintage 30's, but your cab uses Greenbacks, the tone will be different than the amp maker intended. Given, you may prefer it. Using the Kemper's profiled cabs, you can use many different cabs and speakers to best match the tone you're seeking. With a cab you are limited to that cab. With the Kemper Cab Maker you can import 3rd party impulses to try different tones, as well.
So as I said before, some people just love their cab and never want to give it up, as is their right. If you're on the fence, it's likely because you're not emotionally attached to a cab. I suggest trying the FRFR. If you're like some people here and just can't get into a mic'ed guitar sound and want your cab back, at least you know. I'd start with the most tonal diversity. If you have a cab or can borrow one to compare, all the better.