the mini 1-slots are good due to their size.. they're barely larger than a cart. the large 1-slots on the other hand have extras like joypords, memory card reader ports, etc. depends on your needs.
I have a 1 slot which i like with the extra ports such as headphones too and a flip switch to mono/stereo unlike 4 slots,however on the downside the board is open air and its can get dusty and also as you only have 1 game,when you want to swap over you need to be careful when you pull the carts out as ther are very tight and if you pull hard enough like i do you will end up keep hitting the elements on the board to weaken them,i have heard that you can get a cover for it though but all in all i agree the one slot is cool
Only cost me 50 uk pounds. It's got all the slots, 2 mem card connectors, 4 joystick inputs(2 of 2 types), mono/stereo switchable output and headphone sockets.
Always been 100% reliable and it's never covered up. It's an arcade machine, it's supposed to take grief and survive.