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Lots to consider if you want a detailed discussion. The TPI configuration with long runners and small diameter tubes provides a bunch of low end torque. This system performs well when combined with numerically low gears and/or overdrive transmission. If you plan to run at 1400-1700 RPM on the highway or love doing burnouts with a lower hp engine then TPI is a nice choice.

TBI like the Sniper or a GM system can provide more consistent fuel delivery than a carburetor. Your choice of intake manifold really determines whether or not the TBI makes power where you need it. If you replace the TPI on a stock engine with a short runner, small plenum production-type manifold with TBI it's possible you will feel the vehicle has lost performance off the line.

Tuning an efi system can be a challenge. Aftermarket systems often have features built in to make tuning easier. They don't always work as expected and you may need professional assistance. Tuning a GM computer can be more challenging. Most of the work to figure out what to change falls on the owner or tuner. Many folks figure it out but there is a steep learning curve. Some folks just offer to pay to have it done.

The age and power of the computer makes a difference in how well the vehicle responds. For example older TPI systems with a mass air flow sensor will benefit to an upgrade from a 90-91 Corvette or 91 Camaro ecm. TBI systems from late '80s to early '90s cars and trucks can benefit from an upgrade to the 94-95 GM Pickup truck pcm. These changes require reworking the wire harness and can be intimidating to some people. Aftermarket systems may or may not have more powerful and more reliable computers. Aftermarket companies may not have the resources available to spend millions of $$ on research, development, and testing of their controller.

I wish the answer was simple, but all those words really boil down to "It depends." Good luck.