I have a Suzuki Hayate 125 and I found out that the alloy-wheels I have support both tube-tyres and tubeless tyres. I want to ask which are better and why?

Opt for tubeless for obvious reasons ,no more tedious visits to repair punctured tubes ,which happens to me at least once a month sometimes more.
And yeah farangs get charged 50 baht more than my thai girlfriend,so now i send her if problems hehe.

Honestly most benefits from tubeless tires are only noticeable at speeds you probably never ride your 125cc Suzuki Hayate scooter.

Especially when you riding around in the outskirts of Bangkok or even the rural regions of Thailand I would think twice before using tubeless tires on a scooter. If it was a sportsbike I probably would think different, but than I bet you not hang into a corner to much with a Suzuki Hayate 125cc.

If you buy inner tubes for your tires, don't buy the cheapest... they get leaks easily, second take your time to change the tire and check if something punctured the outside tire before you insert the inner tube...