I really like the X series M4 that I got. It's shooting beautifully on a 9.6 2000Mah. The externals are quite amazing, not only looks wise, but also for durability, my old CA M4 proline has been abused A LOT and nothing has every broken or gotten loose. Paint scratches are the worst it has.
VFC E-Series w/ R-Hop, Seige-Tec gears, Lonex Titan motor,
TM Five-Seven unmodified