I just got a nemesis clone from fasttech and I'm just blown away by the quality for the price. I paid right around $25 - an awesome deal. The nemesis clone is really versatile. It fits all my batteries and even can use an 18650 with a kick.
As long as you get a good one, I couldn't recommend the nemi clone more highly. The pros are that it's light, versatile, good looking, small (nemi in 18500 mode is smaller than Magneto in 18350 mode). The performance is really good, too. I haven't measured voltage drop yet but I can tell it's better than magneto and at least as good as my brass sentinel clone.
The only con I have is the switch is just a little bit wonky. Mine isn't wobbly or crunchy but I do need to press it in the approximate center and the mod leans a bit when setting upright unlocked in 18650 mode. I ordered the magnet upgrade for $2 (gotta love fasttech) since I heard that makes a nice improvement in the button action.
The thing about fastttech to be aware of is that they buy things in large batches. So maybe they buy 10000 nemi clones and everybody loves them, gives them high reviews, etc. But when that batch runs out they buy another batch which might be slightly different. You can never be 100% sure what batch you're going to get. Sometimes (a lot of times) the item says it's in stock but it's really not and your order waits until the next batch comes in. Overall, though, I've been really pleased with the stuff I've gotton from FT. I only have 1 "high-end" mech and, as much as I like it, I can't really justify the price over what I get from FT.