to say the least

at the very least

at least; as an absolute minimum; emphatic form of at the least.

final say

The right to make a final decision.

have a say

To (receive the opportunity to) voice one's opinion.

I'd say

It is my estimate or opinion.

I'll say

Used to indicate emphatic agreement

let's not and say we did

Indicates that the speaker does not agree with a proposed action, and does not wish to participate.

needless to say

Clearly, obviously.

not in the least

not at all, not in any way