I'd recommend a simple Taiwanese/Chinese chaintool, with a little hollow screw opposite the pin, which locks the chainlink into position. similar to the one pictured here:
the locking feature is the important thing: it guarantees, that the tools pin moves paralell to the chain rivet.
I prefer them to Park CT-5, Eldi 49, VAR 303 pliers (the latter two on- topic tools9 and various other products.
they should be less than/around 10 \u20ac/$/lb.