I’m in the process of purchasing a new boat, nailed it down to either a 593ht or a 643ht. Both very similar spec, both 4 stroke.
593 has a 150hp Yamaha
643 a 200hp Suzuki

I’m in two minds which one to go for, 643 is 10k more. Is it really that much more of a boat? Yes the extra room would be nice, cabins are identical.

What’s everyone’s thoughts, what would you choose and why? I need help deciding!

Depends on a few things really. e 643 will certainly be heavier to tow. but it would be more suited for offshore fishing. Make sure you have the space to store it also. I'd expect the 593 will go well with the 150 on the back and if you're not heading out into open water then the 593 would be fine. It would still be ok for heading offshore.