The budget ones I prefer is at 37 Dundas Street, MK.
Both are in the same block, floors 2 and 8 but I've been told a new one is opening soon on the 5th floor.
Now the layouts of both are the same, they are tiny compared to ones I've previously gone to, there's about 5 or 6 rooms, 2 large that can accommodate 8 people in total comfortably, but the smaller ones, which are meant to be for 4, frankly fit 2 and I'm a wee guy!
I believe they are of the same owners due to the design but mainly because when they first opened, they were sharing girls between them. ie. If it was super busy on the 2nd floor, they'd call for more from the 8th and vice versa. They've supposedly stopped doing this due to customer/profit targets for each venue so there's no point going to both if there was nothing you saw that you fancied. Now if you see nothing, just head to the next one.
Unless you arrive early straight after work, say 6-7pm, it's normally packed. It gets busy from 9pm. However, they open at 10am I think and there's even a discount before 1pm, I think $350 per hour at the KTV room or taking her upstairs for 45 mins.
Now don't expect stunners or young 'uns, most are between 4-6, I've seen a couple of young cute ones with great bodies but they are normally fully booked so you need to be a regular to get to know the names and the mamasan.
But like I said, for a fun cheap night out, it's a bargain compared to any other place I've ever been in HK. Esp. when 99% of the girls expect you to take them out.