I can guarantee you that the limit is not the lens, but in this case, the photographer. Only you can explain what wildlife, and what "spot" (do you mean sport?) photography. After all, different wildlife (bugs vs birds in trees vs a lion in the savannah) will need the right equipment and skill, and different sports and venues, and *where* in those venues you are sitting, and what the lighting situation is, will determine what equipment you need.
