It is easy to say that the cost will be forgotten once it is paid for, but next to the floor plan, cost can be a deal killer.
We spent over two years debating the type of TT we thought would meet our needs. We even rented a TT similar to the size we thought we wanted. I our case a standard TT won out over the TM and any of the egg units. We found a three year old Dutchmen for about half the price. You can buy a lot of gas and storage for the difference.
But, if you find the TM or eggs are the best fit for your needs, they do maintain their value.