Well, after you travel into the future, buy them, and send those Prime toys to me, I'll give you a thoughtful answer. Though if the TF Wiki is to be believed, they are one and the same. Despite all those problems that have been pointed out to near the point of ad nauseum.
When the Prime toys are finally released, I'll personally go back 600 pages, find this thread, and tell you my opinion.
Get back to me when, oh, we have any friggin clue what the TF: P toys EVEN LOOK LIKE. Seriously, what do you expect when you're asking for comparisions to toys that have not even surfaced yet?
ignoring the fact that they're both the same continuity, Transformers: Prime toys haven't even been leaked yet.
Considering we haven't even seen a single image of any of the TFP toys, and know little more than "they're working on them" for the time being, I can't honestly, or accurately, say which is better than the other. Although if the toys end up anywhere near show-accurate, I'll definitely like them more than the WFC toys. None of which have really wowed me. Also helps that I like the Prime designs more than the WFC designs.
A better question might be would your prefer a transformers prime toy line or a WFC one? My answer would be a WFC line
How could we tell? We haven't even seen the TF Prime toys. Well, this is irrelevant, since the asthetics are different. That's like saying you can't compare Armada toys to Cybertron toys because they're the same continuity.
With figures like TF: Prime Kremzeek and TF: Prime B.O.T. the WFC figures don't stand a chance. Might as well compare Go-Bots to MP figures.
Prime reminds me too much of both Animated and Beast Machines (mainly the cartoony faces and Popeye arms), I'm not a fan of the aestethics so far. WFC on the other hand is a great blend of old and new, I love all 4 currently released figures and love most of the concept art for all other characters.
I cant make a call since prime toys are not out of course but i do like the looks of WFC characters more. TFP has character designs that i am kind of mixed on. The movie and animated crossover is interesting but i do not think it is effective for all of the characters so far. I do not like Prime from Prime but i think Arcee for example looks great. TFP toys could be great or they could be bad till we see them i cant make a call. Now if i had to choose either a TFP or WFC toyline i would say WFC hands down.
Oh Prime toys, hands down. These things are light years ahead of that WFC garbage. Prime toys are probably the best transformers, nay, best toys EVER! Just by holding them radiates a feeling of euphoria. They're so easy to transform, yet so intricate. Damn these are cool toys!!!