The system doesn't have a seemingly infinite number of Catchers, as it seems to with Starting Pitchers, but I do need some line to act as a base, so I'll limit it to guys 25 or younger (no Kratz, no Lerud) who have played in the US. Again, I will do my best to include no bias in the overview of players, and players will be listed in alphabetical order.
Tommy Joseph - Currently playing in Triple-A
Strengths: Plus power potential for a Catcher. Strong arm, athletic. Reknowned for his leadership, considered one of his primary strengths. Strong defensively.
Weaknesses: Patience is an issue, low BB, high K player. Negates some of his power. Power has been spotty and only really blossomed in the California league, the most offensive environment in the minors. Won't hit for average.
Gabriel Lino - Currently in Extended Spring Training
Strengths: Potential for Plus power, plus throwing arm, and, with considerable work, maybe plus defense. Has exhibited good plate discipline in the past with fairly low K rates, combined with good walk rates. Good pop times
Weaknesses: Swing gets long and causes him trouble with off speed pitches, which could make moving up the ladder in the Minors challenging as off speed pitches become more common and better. Defense is very raw, struggles with blocking pitches and occasionally drops more routine pitches. Big player who could grow out of Catcher as he continues to grow. Athletic enough that defense can be expected to improve, may need some swing overhaul.
Cameron Rupp - Currently in Double-A
Strengths: Solid defensive catcher with a strong enough arm for the position. Exhibits good footwork behind the dish. Coaches have spoken positively about his leadership ability. Patient hitter who will take walks.
Weaknesses - Oldest of the Catching prospects in the Phillies system at 24. Some of his success at the plate could be the result of being on the old side for the leagues he succeeded in. Gets tied up by inside fastballs. No individual tool stands out as being particularly good, but no particular tools stands out as being particularly awful either.
Sebastian Valle - Currently in Double-A
Strengths: Plus to even plus-plus power potential is Valle's calling card. Valle has grown into a solid defender behind the plate with plenty of arm for the position and enough athleticism that he can move to other positions if needed. Only 22 years old.
Weaknesses: Valle does not walk (his walk rate is abnormally high this year at ~6%, which would be low for most serious prospects). Valle is not an elite contact hitter and strikes out at a roughly 25% clip. Plus power is nice, but if you can't make consistent contact it is difficult to harness and show up in games. While young, the clock is ticking as he has to be protected on the 40-man roster.