[dave6]

So his line is:

Preflop: minraise
Flop: minreraise
Turn: bet 1/4 pot
River: bet 1/4 pot/minreraise

How had this guy been playing previously? This looks like a typical donkey line with a monster. If he wasn't doing much preflop raising, I'd say he has AA/AT/TT (AK-AJ wouldn't reraise the flop and KK-JJ wouldn't reraise the river). If he's raising preflop more often, this could easily be a flush -- maybe ace high, maybe not. I doubt it's a straight since the river didn't complete any OESDs.

The less he's been raising preflop, the more inclined I am to get more chips in on the river. If he's playing tight preflop, the only thing I'm really scared of is AdKd.