It really depends on what you like. If you haven't been quilting for very long, I would advise thinking about only the *next* quilt you want to make. And honestly, I don't think the Qube is the best way for a beginner to start. It is ***very*** expensive, especially if you don't know yet which size block is most attractive to you, and there are a ***lot*** of quilts you can't make with the pieces. I recommend starting out with a specific quilt in mind, using either a one-piece die or a BOB (block-on-board, meaning all the pieces for a specific block) die.
Here are links relevant to making the Fun Patch quilt:
http://www.quiltingboard.com/main-f1...k-t280816.html
http://www.accuquilt.com/shop/go-hal...rectangle.html
A tumbler die is another fun die to start out with. The small tumblers are great for baby quilts; the large ones for fast quilts. This and other shapes that are difficult to cut with a rotary cutter and ruler are a good way to start out with a die cutter.
https://www.pinterest.com/pin/27021666485178978/
http://www.accuquilt.com/shop/ssearch?q=tumbler
Or, choose a block you want to make and buy the BOB die for it:
http://www.accuquilt.com/shop/ssearc...%20Dies&page=1
I have accumulated about 35 Go! dies over time, most of which I haven't used yet. Many of the shapes in a Qube I have already, as they are part of the other dies. What I find the Go! most useful for is cutting odd shapes (tumblers, circles, hexagons), cutting triangles (but triangles are included in all the block dies I have so I don't need separates), and applique patterns for freezer paper applique (I cut the freezer paper using the Go! -- great time saver!). Other people really like it for cutting strips, but I find that I generally prefer to cut strips with my June Tailor mat so my strip dies don't get used (even though they were expensive).
My 22 cents worth of advice.......