Had both.
1200 was light(199kg claimed), flighty and poorly made (mine was, anyway, see lawsuit threat against BMW UK after 9 breakdowns in 8 months) too clever for its own good with the CAN-BUS system, but it was smooth, quiet, nice gearbox.
1150 is big, heavy (mine's the ADV with luggage, comes in at 250kg)
Tractor, more rugged, less smooth, but planted to the roadsurface.
Entirely up to you. Try both for a day if you can, not just a whizz round the block. Your physical size also makes a diference. I'm 6'4 and 17 stone. The 1150 is perfect for me.
I got the lemon 1200, many have done zillions of miles with no problems at all. Many 1150 owners have drive problems. Six of one, half a dozen of the other
I personally love my 1150 and wouldn't change it for the world.
OK, maybe a night with Mila Jovovich, some custard and a video camera, but that's about it.