As a very part time keeper I'm probably talking crap, but I'll give it a go anyway!
The best catch I've taken with the glove on was off the opening bowler. He'd come back for a spell at the death and was charging in. I was keeping and chose to stand up because 1 it was staying low and 2 the batsman has been going for a walk. Because of the pitch and the fact I was closer I was making a concious effort not to start coming up until the ball had pitched (something I picked up from a keepers masterclass I'd seen somewhere, maybe a Geraint Jones one on the BBC).
The bowler pitches one up outside off, batsman swings and gets a stick and as if stayed low until it pitched I came up with the ball and it just hit the gloves. I suddenly looked gun and we went on to win the game

Moral of the story, don't stand up unless you have to, keep low and watch the ball!
As a final thought, the Billy Big Bollox routine of standing up to everyone is more detrimental than beneficial in my opinion. Ive seen it done a few times where it results in more byes and dropped catches than standing back would've resulted in.