Well, I think that with *any* compressor you are going to have an interaction with the original track, so in that respect there will be a change. I mean, that's why you want to use the compressor in the first place, right? To change the sound in a hopefully positive way.
With some compressors though you may not want the original tone changed much or at all, and just desire the dynamics altering aspect of the compressor. So a relatively uncolored compressor is what you would want to use. There is a lot of grey area here though, as even an "uncolored" compressor can be very noticeable if the compressor is laid on thickly. And likewise, some compressors known for their color, like the Distressors, are very very clean if the compression is used lightly. So there is a large area for debate.
The other thing is, it takes time and experience to learn what compressor sound you like on your music, and which compressors do what to the tracks. I've bought and sold a number of compressors because I thought they might be good for what I wanted but weren't. I've also kept those that I find I like.
For example, I love
my DBX 162. This particular unit was made in 1978. I find that I like the sound of putting this on digital tracks that are a little too "pointy" if I may use a totally subjective term. The slowness of the old compressor and the slightly thick tone just tend to take the edge off the tracks and make them sound that much more pleasant to the ear. At least to my ear. So now I know what that sound is, and I'm gradually learning how to use it. Same with my other compressors, all of which sound different.
Because of the very interactive and personal nature of compressors, I find it a little hard to offer cut and dried type advice about them. It's more like you need to figure out what sound you are going for, and then take it from there. For "uncolored" compression on a budget I'd recommend the RNC, or used Aphex Expressors. In a way it's easier to find compressors that add their own specific color to the sound, and it's also a lot of fun to use them that way too.