Well, tp is right. Technically ALL keyboards are mechanical except for those laser projected ones or touch screens. However, for the purposes of distinguishing between "normal" keyboards and "mechanical" keyboards, if it has an individual metal spring in the mechanism for each switch, it is considered mechanical here. Rubber domes do not, Topre do (and they do contribute at least a small amount to the feeling of the switches, so they don't feel quite like any other "rubber dome" board).
Try to find a local store that stocks Realforce boards and ask if you can try one for an immediate short term reference. Or join the DT tour for a longer term experience, which will be much better.
IMHO, you have to try Topre before buying as they don't appeal to all. Like me, for example. I'm a Cherry MX ErgoClears guy (62g variant), don't like the feeling of Topre switches. Also, BEST is completely subjective. Some consider Alps to be best, others Topre, others Buckling Spring, others some variant of MX. I withhold judgement until I have tried them all for while. I have found my favourite MX variant (for now, but I still need to try Ghost Blacks and Panda Clears, but I will when my Black switches arrive) and prefer it to Topre and my Model M, but I have yet to try a Model F or different Alps variants long term.
One problem is if you find something you really like and use it a lot, everything else feels "worse" simply because it feels different. That's why you have to try it for a length of time so you can get used to the difference and be more objective.