Unit Analysis by Team BethelFrankel
Class
Standard Cross Converter.
Overall
A-
(SS at BT3)
Advantages
+At BT3: Preemptive conversion is vital
+Cross conversion generates a lot of tiles, at minimum
+X shape conversion can be very useful in certain situations
+Better single-tile DPR than Barton due to %HP cut and decent sniper chain
Disadvantages
-Awful CD without BT3
-The actual pattern of cross conversion is awkward for high-damage set-ups without other forms conversion or some RNG
-Unfortunately competes with Barton for the Cross Converter slot in Water.
-%HP cut is quite inflexible to trigger
Explanation
Cross converters are radically different based on if you have obtained their relevant breakthroughs or not (usually MBT, though Ruby only needs BT3). When not fully maxed, they're clunky (if serviceable) options for large amounts of tile generation, similar to Raphael or Uriel.
However, once they obtain preemptive strike, they are arguably the best non-whale units in the game and have a staple slot on basically any team that demands high tile count. While Preemptives should carry you through 90% of the game, obtaining MBT Cross Converters should be a long term goal, as they become simply meta-defining once obtained.
Ruby is a bit of strange case. It's about as hard to get her to the point where she's SS tier as it is for Barton, but Barton is more likely to be obtainable for F2P accounts due to how the five-star unit pool tends accumulate.
With all that said, preemptive cross conversion is the main reason you'd run either, and her X shape conversion, HP cut, and decent ST DPR allows her to be more useful than Barton in certain scenarios. She's definitely worth running as a premier whale converter if you have her at BT3.