I think your desaturated style works better in the black and white that you posted first, rather than in the colour. At least in the black and white it harkens back a little to the film era and an older age of photographer; whilst with the colour ones most appear simply to be the result of forced to shoot through thick glass and detracts from the overall appeal - taking on more the appearance of accidental lack of understanding at the shooting/editing phase rather than a clear creative choice by the photographer. I can certainly sympathise trying to re-create an older appearance in photos taken with modern gear and even trying for a more artistic line in desaturation use, but at the moment I think you've got to work more on the capture and then again on the editing to move away from the accidental appearance and more toward a deliberate choice appearance.
I'd also say the first has the most appealing composition - a clear leading line with space to move into and a good capture of the swirl from the smoke as, I assume, then change direction.
The others appear more haphazard in composition - the 4th for example - is somewhat split between sky and the land, making it feel like two separate entities and what with the focus directed at the plane in the lower half one feels that the block of sky above should be at least cropped out and, when originally taken, should be the spot where the plane and blue smoke should be.
As for the watermark I'm of the opinion that a stylised signature or symbol is pointless unless the person using the symbol has put enough into marketing that its a well known brand. Nike can use their symbol to show their wears because of such a marketing move - whilst for the smaller time professional and amateur its pointless as it serves no meaning to the viewers. Better is a short name or website address - things that can lead back to you the creator and clearly identify the "who" that the copyright is claiming to protect.
I also second the points regarding its somewhat gaudy display, especially in light of the desaturated appearance that you are trying to perfect.