Which claw machine in Jap do u recommend
The bigger "branded" stores and the machines facing the streets as those have higher payouts to lure the crowds in. If you don't mind older series toys, some machines have insanely good payouts because they just want to get rid of them, easy to identify because they tend to be the cheaper ones to play as well. And of course if you really want something, just hog the machine and play slowly, staff will usually come by to help if they see you there for a long time.
The two claw type tend to be easier to win if you have some skills. The 3 claw type tend to depend more on the payout rate than skill. And of course, the more popular the merch, the harder it will be to catch, I've seen machines for popular series which are next to impossible to win as well and usually for those staff will not be as helpful, maybe just positioning it in the original position.
Avoid those on shoutengai (shopping street), as those are usually operated by individuals and the payout rate is bad and usually no staff as well.
if you really enjoy playing then i would recommend visiting stores in the suburbs rather than the city center as they are usually much bigger and seem to have endless variety.