If you only have one option, take Photoshop. You can do nearly every design related task with it. It is the Swiss Army Knife of the design world.
On the other hand if you spend most of your time fiddling with interface layouts. Sketch is much faster and has fewer, better tools (although now some of those are appearing in photoshop).
It's a Swiss Army Knife vs a Machete. If you're clearing brush, which will you choose? Sketch costs two months of CC, I'd say if you're an interface or product designer it is well worth it.
The tools are better at different things.
If you only have one option, take Photoshop. You can do nearly every design related task with it. It is the Swiss Army Knife of the design world.
On the other hand if you spend most of your time fiddling with interface layouts. Sketch is much faster and has fewer, better tools (although now some of those are appearing in photoshop).
It's a Swiss Army Knife vs a Machete. If you're clearing brush, which will you choose? Sketch costs two months of CC, I'd say if you're an interface or product designer it is well worth it.