personally I believe
in my opinion
in my view
to my mind
in my estimation
if you ask me
to my way of thinking
from my standpoint
as far as I'm concerned
in my humble opinion
I reckon
the way I see it
I imagine
I sense
I suspect
personally speaking
I expect
I surmise
I estimate
I gather
I presume
I suppose
I anticipate
I fancy
I understand
I assume I envisage in my judgmentUS in my judgementUK if you ask