In the 50cc range an aprilia RS 50 is probably your best bet, however the reason you have been advised to get a scooter is quite simple, they are automatic. The advantage of this is not obvious until you’ve ridden a 50cc geared bike, the problem is you need to shift gears every 10 mph, which gets tiring quickly, the scooters being automatic don’t have that problem. In 125cc it’s not so noticeable. My personal advice, probably isn’t very helpful, would be to ride a scooter for a year, as they are easy to sell on, and then upgrade to a 125 next year.. but if you are still adamant you want to get a geared bike the RS 50 is the bike to get.