That's dependent on which would be more useful. I use my phone more like a tablet. I use a laptop reading and responding to forums like this, among many other things. You have to look at the Pros and Cons. For me the Surface Laptop seems more my direction.
I think it will be better to wait 3 days and then decide which device will better suit your needs. But I do not expect any changes in form factor, only update of inside components.
That's more to what you need more. Surface Laptop is a traditional laptop with a 3:2 form factor, which adds up to productivity a lot.
If you need a laptop primarily, then go for Surface Laptop.
If you need more an All-in-One device that is a laptop alternative, then wait for the new Surface Pro.
Entirely depends on your needs. Do you need more of a laptop? Then get the Laptop. Is drawing important to you and will you be doing that often? Get the Pro.