You wont be able to use a TC on either, well you will, but it will be awfull. They are both budget lenses and wont be very sharp at the long end and adding a TC will just make that even worse.
Its been said in a thread posted by you before, if you want long glass, you have to pay the money. There is no way around it.
Out of those two, I think the tamron gets slightly better results.
make sure you buy the correct mount this time ;-)