That electric fireplace (assuming it is the 400W one in your other thread) would not cut it. Are you sure it is 400W and not 1400W? Most small space heaters are usually in the 1500W range to give you an idea. Most of the electric fireplaces that I've seen are also about 1500W. The 1500W rating is common since it can go on a 15A circuit with a bit to spare.
With electric, watts are watts. It doesn't matter how it is done (oil, ceramic, halogen, ect.). Any will heat the same space with the same number of watts. One exception is radiant style heaters that will make you feel warmer when standing in front of them. These are good for workshops and similar where you have a large space, but maybe only a couple areas where you primarily work. The radiant style will keep you warm without having to really heat up the whole shop.
On most of the space heaters and baseboards, they seem to be rated for about 10W/sqft. This means that you would need 5000W for your space assuming those numbers. However, we need to know more about your setup to really know. Insulation levels, is the basement fully below ground?, your location/design temperature, size/location of exterior doors/windows, air infiltration rates (new home/old home), etc. 5kW of heat would almost certainly keep that space warm, but you may get by with quite a bit less. Although, with electric resistance heat, having a system that is too big is not a big deal. It will cost more upfront, but won't cost any more in operating costs. A larger system will also bring the temperature up quicker, which could be important if it is a space that isn't used much (setback heat most of the time and kick the temperature up during those times that you use the space).
For running new ducts, that is also a possibility, but it depends on how your system is sized. Often, systems will be sized large enough to heat the basement (assuming the basement was unfinished when the system was installed). Again, we don't know enough about your system to know or whether 2 ducts will be enough to heat the basement space or whether adding those additional runs will steal too much heat from the rest of the house.
Assuming your system was large enough, I would be inclined to heat/cool the space with your HVAC system. Then also add a small amount of baseboards or an electric fireplace incase you need things a little warmer. Since your t-stat is probably on the main level, your basement may be a little cooler than the rest of the house. Instead of cranking up the heat for the rest of the house, the electric fireplace/baseboards can help take the chill off.