The Twin Commanche is faster. The Aztec is roomier. The Seneca is a little closer to modern and like the Aztec, has very mild flying characteristics. Of the three, the least relatively underpowered is the Commanche, but it will also bite you if you get it in the wrong place.
All three are typical underpowered light twins. You gain an advantage in speed and rate of climb over a single such as a Cessna 206 or 207, but at the sacrifice of safety in the event of an engine failure; both are going down, one just does it faster than the other (while facing directional control issues). Properly flown, any of them can be comfortable airplanes.
We had a twin commanche at an ag operation where I flew years ago. I never liked it. The Apache and Aztecs were great airplanes, but slow. Nice headroom, if that's important to you. The commanche was more like flying a mooney; small inside, and had a similiar ride. I flew Senecas for a time off rough fields and to some remote locations in the mountains. I mostly flew the Seneca II and III, which are turbocharged and do much better at altitude. As a light twin, the II's and III's were some of the few that could maintain 8,000 on one engine with a full load.
Bear in mind when shopping for a twin that it's not a slight increase from single engine ownership. The retractable gear, second engine, and increasd maintenance, added insurance, larger tie-down or hangar space, and so on is more like a three fold increase in costs, vs. a two fold increase. Older twins can be had for a good price, but at a price. Have a very thorough inspection done. I've seen a lot of singles that run thousands of dollars at the first annual inspection, due to the things which need to be repaired. I've seen twins run considerably more.
Fly them all and see what you think; get the pilot handbooks and run the performance numbers for the different scenarios in which you envision using the airplane, and see what adds up. Remember that each of those airplanes were originally type certificated under regulations not requiring actual performance numbers (much of the data is interpolated, and is ideal for a new airplane with a new engine and new propeller, flown by a factory pilot under specific conditions)...and none of them were required to maintain altitude on one engine with any significant load.
Good luck.