T-45, T-51, T-60 or X-01?

What do you mean "technically"?

X-01 is the best.

yeah x-01 is the best

X-01 I'd guess, I crossed the glowing sea with a leaded set (MK IV) without losing a single piece of armor, while the T-45 almost got shot off me while fighting raiders......i've never used the Raider, T-51 or T-60 yet (although I have a set of each, well two T-60 with BOS and Atom Cat paint jobs).

I was just curious because I've stuck with the T-60 most of the time and have it upgraded to T60F, was just thinking of what to spend the aluminum and adhesive on next.

The later your grade, the more upgrades are available, and the more effective all the defensive stats are, especially after upgrading. Thus, unless you own an old suit at Model F and you don't have the materials to upgrade your new one, X-01 is ALWAYS the best, followed by 60, 51, 45, and Raider in descending order.

Depends actually. Base Power armor, then yes X-01 is the best one. But if you get Unique pieces from a certain questline, well then it could be different.

X-01 says the Fallout 4 Book

X-01

The overall design, aesthetics, hydraulics and electrical robustness make the T-51 technically the best. The X-01 offers the most protection though.

Well i have a T-60 BoS Paladin Power armour with unique pieces gained from questlines and the BoS vendor. I've found it to be the best in game as of now.

Personally, I love the look of the X-01. The way that the pauldrons blend in with the oversized back plate, giving it that mirelurk shell kind of look is neat. And the asymmetric hoses on the helmet gives it a more unique look. As for the other things, I assume you are talking about Fallout lore? Seeing as they all use the same frame in the game...