I climb hills of up to 15% with the 1000 W geared hub motor I bought. It is a generic 48 v LY . The only thing geared hub motors won't do is 15% for 25 minutes straight - that will burn the winding. There are grades like that in California, Colorado, and Washington, but not here. Since 90% of US ebike sales are in those states, those dealers warn everybody not to buy geared hub motors. I cover 77 hills including 3 15% hills of 35 m in my 30 mile commute, which I've been doing for 18 months. We have rolling hills here in Indiana.
One other thing about hub drives. Install a 2nd set of lock nuts on the axles. That keeps the nut from coming loose and the axle slides around. I removed & replaced the rectangular sensor connector to do that. I also installed 12 cm thin 1mm torque arms made out of bed frame rail. The common torque arms sold here are ~2.5 mm thick, made of *****y imitation steel is my guess.
If you want a mid drive it is best to buy a bike that comes with it from the factory. There is machine work involved in modifying the frame for a bosch. If an aftermarket conversion, the bafang mid drive is not as difficult to install. Surly has a factory installed mid drive model. The bosch mid-drive requires you to drag the motor with your feet if you wish to pedal unpowered or the battery connection fails.
Note crimped on 3.99 mm bullet connectors or 6.35" flag terminals (from taiwan,T&B,Ideal,Panduit,3M) are more reliable connectors than the push on battery connections of most factory battery bikes. I've had zero battery interruptions in 2 years. I have an XT90 connector on the harness that came with the battery, but those factory welds are also reliable. My personal XT90 solder joints are not nearly as reliable - the XT60 solder joint pulled off the charger where I couldn't charge out at my summer camp 30 miles out. The charger came with a round barrel connector I had to change out to XT60 to match the battery. If using flag or bullet connectors, be sure to put a male on minus and a female on plus to make sure you don't plug them in backwards. Pull test crimp before use. Ideal or Klein crimp tools make better crimps than short handle generic ones.