The title pretty much sums it up; if you could choose between being a Transformer or a Mutant, which would you be?
Transformers
Pros: Lot of weapon variability (Energon Swords/axes/maces, guns (both 'human' type, and Cybertronian, so Sonic cannons, plasma cannons, shockwave cannons etc)
Many alternate modes: Trucks, planes, trains, tanks etc. The possibilities are endless.
Extremely durable: You can take lots of punishment.
Strong/Fast: You weigh several tons, move fast (in some cases) and very strong.
Intelligent: Intelligence is on a human spectrum.
Cons: Vunerable to electricity (assuming Transformers have no way of dealing with it, though I'd imagine they are surge protected haha). Magneto could crush them into a tin can unless they did an unexpected attack or something.
Mutants
Pros: Tons of powers. Storm, strength, magnetism, speed, intellect, shapeshift, animal senses etc.
You're still human, so you can do all the human things.
Intelligence: You are smarter than the average human in some cases.
Cons: You still have a human body (though some mutants rectify this by hardened skin etc), and the limitations with it.
Personally, I would choose Transformer, but if the mutant power was desirable, I would take Mutant instead.