I too am in a similar situation and looking to buy an Axe FX II XL+ and everything to go with it later this summer.
However by reading through many of the threads on here I've come to the conclusion that for the full effect you need to buy a decent quality poweramp, Matrix GT if you can afford it, but if not then buy the best alternative you can, be aware of what input connections are available on it (XLR, 1/4 jack?) and what it has for output connections (speakon, jack?) to deliver the sounds to your chosen cabs. Just remember that the cabs should be FRFR (again such as the Matrix FR or NL) or as close as possible to this ideal.
A lot also depends on whether you are looking at using this purely in the home environment, in a studio, or out on the road... all of these factors will steer you in the right direction.
As for me, since I gig regularly I will be getting the Matrix GT800FX but not sure if my own wallet can stretch to include the FR or NL cabs since I want to run in stereo. This means I am still considering other options.
Other people can probably advise further on cabs but even then they probably need to know what budget you have available.