Depends on what the options are.
With Brawl I totally skipped the Leader Class because I was perfectly happy with the Deluxe Class which I considered a better toy. With Movie 1 Megatron I got the Leader Class because I didn't like how the ice kibble on the Voyager wasn't removable. If it were, I would have happily skipped the Leader and gotten the Voyager (even if the spring loaded toes bug me). Leader Movie Optimus Prime is actually a very good toy IMO - arguably the best Optimus Prime toy made since G2's Laser Prime.

I got ROTF Leader Prime because it's an even nicer toy! I got ROTF Leader Megatron because I didn't know there was going to be a Voyager Megatron coming out later.

I'm trying not to make that mistake again so I'm trying to find out what toy classes HasTak's planning on making of each DOTM TF. I even
made a thread about it, but nobody's posted.
I got Leader Jetfire cos... well, there isn't much choice other than getting a FAB or Legends, which I don't consider "compatible" with my other Deluxes, Voyagers, Leaders...
I got movie Prime, ROTF Prime and ROTF Megatron on sale thankfully... but paid full RRP ($99.99!) for movie Megatron and Jetfire!

They were both hard for me to find, so I just grabbed them when I could (then later Megatron shelfwarmed... and was put on sale... gah)