A-Rod's numbers will almost definitely improve. His average is low as the BABIP is very low, but the power's there so he has been hitting the ball. I think the average will definitely balance out to respectability moving ahead, so you may want to realize you'd be selling somewhat low on him. Reynolds is a very underrated player as you noted, but I think it's a gamble to anticipate him keeping up his pace and hitting 40+ homeruns and stealing 30 bases, though it's not out of the question by any means. I'd say with that in mind, A-Rod's the surer thing going forward, but Reynolds should definitely provide much more speed and can provide comparable power if he keeps it up which would be an improvement over A-Rod as I doubt he runs much this year.
I'd want Lester over Alexei but I was never crazy about Ramirez.
Only because I'm conservative with my players, I like the other side better, but it's definitely not lopsided either way.
Bottom line, if you think your pitching can afford to lose Lester and you like Alexei, then go for it.
ESPN 12 team mixed points league
Max 162 starts
2 DL spots
C: Carlos Ruiz
1B: Paul Konerko
2B: Howard Kendrick
3B: Ryan Zimmerman
SS: Yunel Escobar
IF: Bryan LaHair
OF: Carlos Gonzalez
OF: Jay Bruce
OF: Ryan Braun
OF: Justin Upton
Util: David Ortiz
BN: Shane Victorino (OF), Chris Davis (1B/3B), Mike Trout (OF)
SP: CC Sabathia, Matt Garza, Shaun Marcum, Yu Darvish, Ross Detwiler
RP: Steve Cishek, David Robertson, Santiago Casilla, Rafael Dolis, James Russell
DL: Kyle Farnsworth, Sergio Santos