>>807181430MM are fine. They're like simple HG gunpla. Nothing wrong with them, nothing to really write home about either. If you like the way they look and the current selection of addon parts available, go for it.
FA vary greatly in quality. Some are real cool, some are bricky or fall apart when you breathe on them. Approach with caution and ask about specific kits before buying.
FAGs are generally pretty nice nowadays, beware of some issues on older ones. Wrists and I believe shoulders are potential areas for breakage, handle with care.
Hexa Gear is just great, and would be my suggestion to you. There's a great deal of modularity, and all the vehicles seem to come with spare parts or extra connector bits for swapping parts around or building. I have been extremely pleased with all my Hexa purchases so far. Perhaps my only criticism of the line is that Governors are fairly pricey for their size, I feel you get a LOT more bang for your buck with vehicles.
FAG, FA, and Hexa Gear work together to some degree, and all three are compatible with Koto's expansive line of MSG weapons sets. This gives you a LOT to work with.
