The best use I found for japanese planes (their setup and aspects may have some use in planing very perfect soft woods, but technically other than that, they will be more demanding in sharpening and less reliable in avoiding chipping - the limit on clearance vs. critical angles to really get good edge strength in a variety of woods just isn't there - they were designed for super clear softwoods where there's a reward)....
....anyway, where i found them useful was when I first started dimensioning. I couldn't last long jack planing, but I could last a long time pushing a jack plane until I was tired and then pulling a jack japanese plane, same with the next step, etc.
Eventually, I learned to plane without getting tired, and also learned to plane left handed as well and that was the end of that with japanese planes. keeping the irons nick free and then repairing said damage with traditional sharpening methods is a pain.
On the bright side most of the inexpensive planes are very good. I wouldn't faff with getting a little one (in case someone suggests you get a 42mm plane or some such thing - they're fairly useless). If you have normal man hands, 65 or 70 degrees will suit you well. You just need something with a white oak dai, a laminated iron and a chipbreaker. hitachi provides white 2 and blue 2 and blue 1 in pre-laminated material so a good quality iron can be made just by cutting an iron out in the right shape (and many of the more expensive planes still do just that - their comments about someone sitting over a fire in the dark can be ignored if the lamination line is perfectly straight looking).