Welcome to the forum Lopper.
I read the review of the Xtracrylix paints in SAM, and they sound quite good.
I have used, Tamiya, Gunze, Model Master, Vallejo, and Lifecolour acrylics, and in my opinion Gunze are the best in terms of quality and colour range, closely followed by Tamiya, same quality, limited colour range. The Vallejo gives a great finish, but I found it somewhat fragile, while the Model master appears to be pretty good too. The Lifecolour is OK, but the pigment is no where near as fine as the first four.
I wouldn't worry too much about only using paints from one range, as I use paints from all of the above depending upon my needs. For example Gunze do an RLM 79, but this is the darkesr shade, not the lighter shade, 79a which Model Master do. The main thing is only to mix paints from the same manufacturer.
Hope this helps.
Karl