Hello Dave:
I had a 1961 1600 MK II. I loved that car. It had 40,000 miles in 1965, when I got it, and it drove perfectly, with plenty of power until an idiot ran a red light and totaled it.
I now have a 1974 1/2 MGB, that I've had for about 6 years. It's a great tourer, comfortable, tight, and plenty of power.
I'm restoring a 57 TR3, that I drove briefly, before I began to fit the body panels. My 69 GTO buddy drove it, and said "this car has balls" I take that as high praise, and it has tons of power. It also has steering slack, rattles, and shakes that the MG doesn't.
Everyone asks what will I do with the MG, once the Tr is finished. Why keep it of course. It's a wonderful car, but I've named the TR "Chopper" as it's not feminine in the least. I had a tr6, and a healey 100-6, and driven a MGC back in 69, and I wonder if a tr3 with the 2140 cc engine, and a weight of 2000 lbs, is actually faster than those 6 cyl.
So it really depends on what your going to do with the car- either one is a winner in it's own right.
Emmett