I would go with a Marshall. The second amplifier I bought was a Marshall 250DFX. I eventually found out I like "tube" amplifiers, which use vacuum tubes instead of the transistors that are used in "solid state" amplifiers like the Marshall, but I still kept the Marshall. It's a goos amplifier, and compared to the squier you have now it will sound much more lush like and refined.
Try it out though I don't want to tell you what to get.