Well, you need to tell us what you are looking for in a light before we can suggest a light. The Tk45 runs on AA batteries - do you only want a light that runs on AA? Would you use Cr123a, rcr123a, 18650, eneloops, 14500, etc batteries? The TK45 is a very floody light - do you only want floody lights are do you want something where the beam travels farther (more throw)? What size light - the TK45 is pretty big - is that the size you are looking for?
As people suggest, HDS are nice lights bet they are in a different world from a TK45. It is like saying you want to buy an Ford F350 and somebody tells you to buy a Audi TT. They are completely different lights so you need to give us more info on what you are looking for.