I was thinking about effects for tube simulation, like Tube Screamer etc. I found three cheap models. Which on is more "natural"?
I found the Behringer TO-800 Tube Overdrive to be a good cheap alternative for the Tube Screamer. Might be worth checking out. The Behringer VT999 Vintage Tube Monster Effects Pedal has some good reviews as well, though I never tried it.
The first one you posted the Xdrive pedal. sounded real muddy when heavily boosted I would just avoid it didn't sound pleasing at all.
The Electroharmonix did sound very nice good bite, with nice crisp leads.
I personally have a Digitech Bad Monkey Drive, which was a knock off of the TS, I got it very cheap. and it if you willing to shop ebay or used you can probably get one for around 20 dollars. Its a very stout pedal solid metal case and can take some abuse. Got that great Blues Drive sound. but not over saturated to the point where it seems like a Distortion pedal.