Comparing a Roland Cube with a Blues Jr. is a prime example of comparing apples and oranges.

The only thing they have in common is that if you plug a guitar in and turn it on, you get some sound out of it.

I have nothing against the Roland Cube.

But the Blues Jr. is one of the best small tube amps out there.
It's sort of a cross between the clean Blackface sound and the rough Tweed sound.
The best of both worlds.

For my level of playing a different speaker is not going to mean a lot so I can't comment about that.

At some point, if you're interested, Google the BillM mods for the B Jr.
Some people swear by them.