I phoned an electrician and he told that the wall mounted type cost more to purchase, instal, and that the electic motor would last about ten years.

If they are both electric resistance heaters, they are both 100% efficient, minus the motor's draw.

Some electric heaters might have their wattage based on 240V.

Depending on the fan, it's going to be noisy. Baseboard is quiet.

tick, tick, tick.

"tick, tick, tick."

Usually a bad installation.

You said one thing in your post that could be a problem - you said you were considering putting the fan-forced wall-mount heater under the window. Usually that is not recommended because they should not go in an insulated wall. (Insulation up against the heater's housing can be a fire hazard if the heater overheats.) Check the installation instructions for the heater(s) you are considering, but generally I believe they should go on inside, not outside, walls. Baseboard heaters are normally recommended to be placed on outside walls, though.

Efficiency-wise, there is really no difference between the fan-forced and baseboard heater. The fan motor uses a little power, but the heat given off by the motor goes into your room, so it's not wasted power. The fan-forced heaters do heat up a room faster, so they are probably better for a room where you may only heat it occasionally, like a rec. room, workshop, etc. The noise factor probably makes baseboard better for a bedroom, although that's kind of a personal issue - the fans are not that loud but some people are going to be bothered by the intermittent nature of a fan turning on and off.

Baseboard heaters are safer. In tests by the U.S. Consumer Product Safety Commission, cotton cloth was stuffed inside several makes of baseboard heaters, and they could not make them start a fire. The fan-forced heaters can start a fire if the fan fails or if too much dust builds up in the heater. Neither type of heater is very dangerous, in the overall picture, but it's something to consider.

As far as purchase price, as the electrician told you, the fan-forced heaters are costlier and they have a shorter life than baseboard heaters because of the fan that can fail, and because the heating elements run at a hotter temperature and they burn out sooner. I have seen baseboard heaters that are 30+ years old that still work like the day they put them in. They're so simple that there's hardly anything to go wrong.