My general opinion. All clones are crap, except as an upgrading platform.
On a scale of 1-10, stock clones shoot a 3. Meaning they can nail a torso sized target at 100 feet once they've been broken in.
The stock Maruzen is probably around a 5 or a 6. It can reach out there but good luck getting shots past 175 ft.
A fully upgraded clone is probably around an 8. They'll shoot on par with a fully upgraded Maruzen, assuming you did it right, but they'll feel cheap and the small internal parts (screws and whatnot) strip and break easily. This is fixable by retapping/buying heavy duty flatheads. Also, upgrades give you twice the headache.
A fully upgraded Maruzen is a 9. Again, shoots the best possible for an airsoft gun, does not feel cheap, and the nonupgradeable internals are higher quality. It's still smart to replace the screws on the trigger mech, stock, mag catch, etc.
Maruzen with aftermarket externals+all the other internal mods and upgrades: dead sexy. 10
This rating is pretty inaccurate because of all the internal options and tweaking you can do. But a stock clone is on the bottom of the list.
Clones are: TSD, UTG, AGM, JG, etc....
There's nothing wrong with clones and with enough work they can be on par with a Maruzen...but that requires all sorts of work. Foaming the stock, replacing small parts, weighting the stock more evenly, replacing the bolt handle, replacing the stock bipod, etc.
Fully upgraded, a bolty can hit 300 ft reasonably accurately. Honestly I find this difficult, but I'm still adjusting my setup. It's all about time and money