Heavy Bag- What Type???

Hi Guys,

So many different heavy bags out there. I am thinking of replacing my existing hanging bad. I have a 75 pound TKO bag. I'm pretty happy with it but want to see what else is avaliable.

My qustions-

What are the benefits of a heavier bag for example a 150 pounder? Is it used as often in Muay Thai and boxing?

Also, should I get leather?

Finally, what type. I am looking at the Title 100 pound leather bag..Who makes the best bag..