If...( and that's a BIG if) there is enough political will on the GOP side to support removal via the 25th Amendment, then there is enough political will to do it via impeachment. Impeachment sends a stronger statement, it could prevent Trump from holding office again, and it can happen a lot more quickly.
Note the second paragraph of Section 4 of the 25th Amendment:
Thereafter, when the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that no inability exists, he shall resume the powers and duties of his office…
There is a lot of whipsawing back and forth before the issue gets settled.
Pence, et al: “Trump is crazy. Mike’s President now.” Pence acts as President.
Trump: “Nuh-uh. I’m not crazy. I’m still President.” Guess what? Now Trump’s still President.
Pence, et al: “We told you. Trump’s crazy. Here’s a letter. Mike should be President now.” Trump
is still President while Congress meets.
…and then Congress takes God-only-knows-how-long to arrive at a decision; a decision which takes 2/3 of
both houses of Congress to remove via this process v. 2/3 of only the Senate to remove via impeachment.
Alternatively, it takes very little time to draft up one article of impeachment (Rep. Omar says she’s got one ready to go), and there is no reason the Senate couldn’t convene, vote on that article, and have Dollhands Donnie out on his ass in an hour or two. Sure, there’d be lots of closed door meetings and whipping of votes, but if removal via 25th Amendment seemed like a do-able option, than impeachment is even easier, and more definitive.
I'll take either one, but the question is - do enough Republicans care enough about our Democratic Republic to act - I doubt it