Oh, I don't know which comic, the theory is pretty well known they will go at it again in the near future.
And the "up-to-date" Batman will have to deal with an "up-to-date" Slade.
Almost everything you see in Slade series is while his powers were dissapearing(Make him more likeable I guess). He even said he wasn't half of what he used to be after he beat Aquaman and GreenLantern.
Now, his powers seem to be back in full like in the beginning, possibly more after seeing what he did to the JLA
Sadly, Slade vs. Tim has happened, and it wasn't pretty. Tim got a hit in, but Slade moved so fast he broke his staff and would have plugged Tim if Bart hadn't saved him. Never mind that Slade was posessed and so probably not at his best. Dick lasts a little longer against him, mainly because of superior evasion skills, but Slade kicks his ass in straight fights. Dick had to pay the guy off for God's sake. This is a toss-up. It's been done, a few times, first time Deathstroke won, but after that it Bat's figured out some counter-measures. He has sort of a Slade fighting protocol. Goes either way, but in a straight fight it's Slade.
__________________ "Oh yes, Tim's smart-- smarter than me...take my word Alfred, we'll end up working for him someday once he does a bit more growing up." -The Batman
Give Priest credit for making Batman into a beast via prep. Specially made gauntlets that beat the Ikon suit, another specially made set of gauntlets that charge up on Slade's staff and can stagger Superman. And even without the toys, Batman was able to hold his own somewhat.
It's just, even with all that, at the end Slade got a cracked skull he would have healed from, while Batman had the tip of a blade in his gut that he would have bled out from. Any way you slice it, Slade looked better against a Batman flush with prep and plot devices..
In a random encounter, restricted to his utility belt, the odds aren't as good..
Back when Marv Wolfman was writing, he outright beat him down. And in Priests current series, he was taking shots from power gauntlets made to beat on Superman, got his head caved in and his skull cracked open, and still managed to slip a knife between his ribs without him noticing.
And then he patched him up and lasered the knife out, later.
As if that's not bad enough, Bruce was wrong about who left the false information about Damian being Slade's son. He assumed it was his wife, but it turns out it was Talia.
Slade figured it out, and Bruce confirmed he was wrong. So, Slade > detective then Batman.