Which one is better by themselves?

I like the Luke starter a bit more because both characters can be played elite (even though you only get one die for Han). And on top of that, Heirloom Lightsaber is a really solid weapon upgrade.

by themselves how?

as in just one versus the other? the cards in one versus the rest of the game?

I personally like the Luke Starter a lot more. Even at one die, Han Solo is a lot more useful in the late game than a Veteran Trooper and the inclusion of the Millennium falcon makes it very easy to win in the long run

Overall, the cards in the Luke Starter are just generally more useful. Boba's only really got Entangle and Crash Landing, apart from the Hidden Blaster both sets share

If you had to pick one for a draft lets say, go with the Luke. Boba isn't a bad choice, just not the better choice.

If this helps, I play only villains and I picked up a Luke starter so that I could have an Heirloom Lightsaber and Force Focus. The extra Hidden Blaster is gravy. I haven’t gotten a second Boba cause none of the cards screams playset to me, except Boba who comes elite.