Mortal Kombat X vs Tekken

I played the MK9, it's okay but not as good as tekken i'd say.
All characters feel more or less the same, girls are all identical just with different colors.
Enemies will always do the 2 or 3 same combos (coz there's not as many moves as tekken) and they'll always guarding or frog jumping away from you.....
I can't say about the 10th MK, but i seriously prefer Tekken over Mk franchise, gore is nice though. That MK9 had less move than Tekken 3, and it's an old PS2 game.

Aside from both being fighting games, I wouldn't imagine they're anything like each other...might as well compare both/either to the Street Fighter games

Tekken Tag Tournament 2 + Mortal Kombat X= MEGA GAME BEST EVER
or character tekken + character MK= cooooooooooooool

I'd say I'd prefer MK over Tekken, yet I'm basing this over MKX and not the entire MK franchise as I've only played MKX.
I love the variations and every character has 10-15 "kombo's" plus the additional variation specific moves. Also, while reading Shawei's comment, he stated that enemies will just do 3 "kombo's" and then they'll just guard or frog jump. This is probably only the case in the easiest sinple player vs AI mode and there's plenty more gamemodes. So I don't think you can judge the game on that feature.

That being said I honestly wouldn't know which one is better or more advanced and I fully agree with RowdyOne.
Maybe try both? :)

MKX > Tekken

"but are they in any way, a lot like eachother?"
Not at all.
MKX uses only 2D movement, Tekken uses full 3D movement. MKX uses a lot of projectile attacks, Tekken uses none.
Those two points alone already fundamentally change how the games play, and then we're not even going deep into the fighting mechanics.