FG with their new list out on the Astros which contains a total of 46 players if you include the "other prospects of note"...
5 or More Prospect Lists (25)RHP Forrest Whitley..............FG/BA/BP/MP/PL/1500
OF Kyle Tucker.......................FG/BA/BP/MP/PL/1500
OF Yordan Alvarez.................FG/BA/BP/MP/PL/1500
LHP Cionel Perez...................FG/BA/BP/MP/PL/1500
RHP Corbin Martin................FG/BA/BP/MP/PL/1500
SS Freudis Nova.....................FG/BA/BP/MP/PL/1500
RHP J.B. Bukauskas................FG/BA/BP/MP/PL/1500
RHP Rogelio Armenteros......FG/BA/BP/MP/PL/1500
RHP Jairo Solis........................FG/BA/BP/MP/PL/1500
SS Jonathan Arauz.................FG/BA/BP/MP/PL/1500
OF Seth Beer..........................FG/BA/BP/MP/PL/1500
RHP Josh James......................FG/BA/BP/MP/PL/1500
LHP Framber Valdez..............FG/BA/BP/MP/PL/1500
3B Abraham Toro...................FG/BA/BP/MP/PL/1500
OF Alex McKenna...................FG/BA/BP/MP/PL/1500
2B Luis Santana......................FG/BA/BP/MP/PL/1500
C Garrett Stubbs.....................FG/BA/MP/PL/1500
OF J.J. Matijevic........................FG/BA/MP/PL/1500
RHP Brandon Bielak...............FG/BA/MP/PL/1500
RHP Dean Deetz......................FG/BA/MP/PL/1500
RHP Tyler Ivey..........................FG/BA/MP/PL/1500
RHP Peter Solomon.................FG/BA/MP/PL/1500
RHP Bryan Abreu.....................FG/BA/MP/PL/1500
RHP Jayson Schroeder.............FG/BA/MP/PL/1500
OF Ross Adolph........................FG/BA/BP/MP/1500
4 Prospect Lists (6)OF Myles Straw........................BA/MP/PL/1500
OF Ronnie Dawson..................BA/MP/PL/1500
SS Jeremy Pena....................... FG/BA/MP/1500
3B Joe Perez.............................FG/BA/PL/1500
SS Deury Carrasco...................FG/BA/MP/1500
RHP Cristian Javier...................FG/MP/PL/1500
3 Prospect Lists (3)RHP Brandon Bailey.................FG/PL/1500
LHP Reymin Guduan................FG/BA/1500
RHP Enoli Paredes....................FG/MP/1500
2 Prospect Lists (5)RHP Manny Ramirez................FG/BA
UTIL Osvaldo Duarte................FG/1500
LHP Kit Scheetz.........................FG/1500
OF Carlos Machado..................FG/1500
RHP Heitor Tokar......................PL/1500
1 Prospect List (21)RHP Carlos Sanabria................FG
RHP Angel Macuare.................FG
RHP Cody Deason....................FG
RHP R.J. Freure.........................FG
RHP Jose Hernandez................FG
UTIL Enmanuel Valdez.............FG
C Chuckie Robinson.................FG
C Scott Manea...........................FG
RHP Brady Rodgers..................BA
UTIL Nick Tanielu.....................1500
LHP Ryan Hartman..................1500
UTIL Josh Rojas.........................1500
UTIL Alex De Goti.....................1500
LHP Brett Adcock.....................1500
RHP Chad Donato....................1500
OF Jake Meyers.........................1500
RHP Cy Sneed...........................1500
RHP Akeem Bostick..................1500
1B Taylor Jones.........................1500
OF Corey Julks...........................1500
C Nathan Perry.........................1500
Positional Breakdown:
RHP--26
LHP--6
C--4
1B--1
2B--1
3B--2
SS--4
UTIL--5
OF--11
FG = Fangraph's "Astro's Top 39 Prospects" plus 7 add'l prospects of note for a total of 46 prospects (retrieved 3/14/19)
BA = Baseball America's Preseason Top 30 Prospects published in Feb. 2019 as adjusted (since the list was finalized before the JD Davis trade, I chose to also include Luis Santana and Ross Adolph who were #13 and #18 respectively on BA's Mets list so in actuality we're talking 32 prospects here)
BP = Baseball Prospectus' Preseason Top 17 Prospects (retrieved 2/13/19)
MP = MLB Pipeline's Preseason Top 30 Prospects (retrieved 2/28/19) plus
Best Prospect Who Just Missed (retrieved 3/8/19) for a total of 31 prospects
PL = Prospects Live Top 30 Prospects (retrieved 1/8/19)
1500 = Prospects 1500 Top 50 Prospects (retrieved 1/28/19)