I'd give up stealth for longer shots and tighter shot groupings any day. However, if you are bent on stealth, the Smart Parts All American is my top choice. It's very quiet and comes in three bore sizes to match whatever paint you shoot. Improved accuracy is the expected benefit from a new barrel Which barrel to get is a difficult question to answer. I know of no person that has enough money and time to buy every aftermarket barrel available and test them.
Testing is very difficult because conditions affect paint and that affects accuracy.
So, for some conditions and for some paints a particular barrel may provide outstanding performance. But for a different set of condition and a different brand of paint, it may not be that great. So, most verteran players get several barrels of different sizes and tightness to match to whatever paint and conditions they face. If you are a player on a limited budget and can only afford a single barrel, then I would get a medium bore barrel. Typically, medium bore will handle a wider range of paints well.