4cyl vs 6cyl chevy s10?

The 4cyl will get better gas mileage, but barely. It might be good if you get a 2wd regular cab, but it seems under-powered for a 4x4 s10. The 4.3L V6 would be the better choice. It has more than enough power, and they are very reliable. If you do need repairs to them, the parts don't cost too much and they are generally easy to install. The only thing you need to watch out for is fuel pumps. I have a 1996 blazer with the 4.3L and it has almost 170,000 miles on it and it still runs strong. If I take off from a stop sign hard, it will still break both rear tires loose and slide a little bit. The only thing I had to replace on the engine was a water pump.